Semiconductor light emitting element

ABSTRACT

According to one embodiment, a semiconductor light emitting element includes a first electrode, first and second light emitting units, first and second conductive layers, a first connection electrode, a first dielectric layer, first and second pads, and a first inter-light emitting unit dielectric layer. The first light emitting unit includes first and second semiconductor layers, and a first light emitting layer. The first semiconductor layer includes a first semiconductor portion and a second semiconductor portion. The second light emitting unit includes a third semiconductor layer, a fourth semiconductor layer, and a second light emitting layer. The fourth semiconductor layer is electrically connected with the first electrode. The first conductive layer is electrically connected with the third semiconductor layer. The second conductive layer is electrically connected with the second semiconductor layer. The first connection electrode electrically connects the first conductive layer and the first semiconductor portion.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority fromJapanese Patent Application No. 2013-138301, filed on Jul. 1, 2013; theentire contents of which are incorporated herein by reference.

FIELD

Embodiments described herein relate generally to a semiconductor lightemitting device.

BACKGROUND

A semiconductor light emitting element in which multiple LEDs (LightEmitting Diodes) are stacked has been proposed. Many light-shieldinginterconnects are provided in such a stacked semiconductor lightemitting element. Therefore, the light extraction efficiency is low.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A to FIG. 1C are schematic views showing a semiconductor lightemitting element according to the first embodiment;

FIG. 2A to FIG. 2D are schematic views showing the semiconductor lightemitting element according to the first embodiment;

FIG. 3A to FIG. 3C are schematic views showing the method formanufacturing the semiconductor light emitting element according to thefirst embodiment;

FIG. 4 is a schematic cross-sectional view showing another semiconductorlight emitting element according to the first embodiment;

FIG. 5A and FIG. 5B are schematic cross-sectional views showing othersemiconductor light emitting elements according to the first embodiment;

FIG. 6 is a schematic cross-sectional view showing another semiconductorlight emitting element according to the first embodiment;

FIG. 7A to FIG. 7D are schematic views showing another semiconductorlight emitting element according to the first embodiment;

FIG. 8A to FIG. 8F are schematic views showing another semiconductorlight emitting element according to the first embodiment;

FIG. 9 is a schematic cross-sectional view showing another semiconductorlight emitting element according to the first embodiment;

FIG. 10A and FIG. 10B are schematic cross-sectional views showing othersemiconductor light emitting elements according to the first embodiment;

FIG. 11 is a schematic cross-sectional view showing anothersemiconductor light emitting element according to the first embodiment;and

FIG. 12 is a schematic cross-sectional view showing a semiconductorlight emitting element according to a second embodiment.

DETAILED DESCRIPTION

According to one embodiment, a semiconductor light emitting elementincludes a first electrode, a first light emitting unit, a second lightemitting unit, a first conductive layer, a second conductive layer, afirst connection electrode, a first dielectric layer, a first pad, asecond pad, and a first inter-light emitting unit dielectric layer. Thefirst light emitting unit includes a first semiconductor layer, a secondsemiconductor layer, and a first light emitting layer. The firstsemiconductor layer is separated from the first electrode in a firstdirection and includes a first semiconductor portion and a secondsemiconductor portion. The second semiconductor portion is arranged withfirst semiconductor portion in a direction crossing the first direction.The second semiconductor layer is provided between the secondsemiconductor portion and the first electrode. The first light emittinglayer is provided between the second semiconductor portion and thesecond semiconductor layer. The second light emitting unit includes athird semiconductor layer, a fourth semiconductor layer, and a secondlight emitting layer. The third semiconductor layer is provided betweenthe first electrode and the first light emitting unit. The fourthsemiconductor layer is provided between the third semiconductor layerand the first electrode. The fourth semiconductor layer is electricallyconnected with the first electrode. The second light emitting layer isprovided between the third semiconductor layer and the fourthsemiconductor layer. The first conductive layer includes a first paddisposition portion and a first inter-layer portion. The firstinter-layer portion is provided between the first light emitting unitand the second light emitting unit. The first pad disposition portion isarranged with the first inter-layer portion in a direction crossing thefirst direction. The first conductive layer is electrically connectedwith the third semiconductor layer. The second conductive layer includesa second pad disposition portion and a second inter-layer portion. Thesecond inter-layer portion is provided between the first light emittingunit and the second light emitting unit. The second pad dispositionportion is arranged with the second inter-layer portion in a directioncrossing the first direction. The second conductive layer iselectrically connected with the second semiconductor layer. The firstconnection electrode extends in the first direction and electricallyconnects the first inter-layer portion and the first semiconductorportion. The first dielectric layer is provided between the firstconnection electrode and the second semiconductor layer, between thefirst connection electrode and the first light emitting layer, andbetween the first connection electrode and the second conductive layer.The first pad is electrically connected with the first pad dispositionportion. The second pad is electrically connected with the second paddisposition portion. The first inter-light emitting unit dielectriclayer is provided between the first light emitting unit and the secondlight emitting unit, between the first light emitting unit and the firstconductive layer, between the second conductive layer and the secondlight emitting unit, and between the first conductive layer and thesecond conductive layer. The first inter-light emitting unit dielectriclayer is light-transmissive.

Various embodiments will be described hereinafter with reference to theaccompanying drawings.

The drawings are schematic or conceptual; and the relationships betweenthe thicknesses and widths of portions, the proportions of sizes betweenportions, etc., are not necessarily the same as the actual valuesthereof. Further, the dimensions and/or the proportions may beillustrated differently between the drawings, even for identicalportions.

In the drawings and the specification of the application, componentssimilar to those described in regard to a drawing thereinabove aremarked with like reference numerals, and a detailed description isomitted as appropriate.

First Embodiment

FIG. 1A to FIG. 1C are schematic views illustrating a semiconductorlight emitting element according to the first embodiment.

FIG. 1A is a plan view. FIG. 1B is a line A1-A2 cross-sectional view ofFIG. 1A. FIG. 1C is a line B1-B2 cross-sectional view of FIG. 1A.

As shown in FIG. 1B and FIG. 1C, the semiconductor light emittingelement 110 according to the embodiment includes a first electrode 61, afirst light emitting unit 10 u, a second light emitting unit 20 u, afirst connection electrode 51, a first dielectric layer 51 i, a firstpad 41 p, a second pad 42 p, and a first inter-light emitting unitdielectric layer 71. In the example, a first conductive layer 41 and asecond conductive layer 42 are further provided.

The first electrode 61 is light-reflective. The first electrode 61includes, for example, at least one selected from Ag, Al, Rh, and Au. Analloy including the at least one selected from Ag, Al, Rh, and Au may beused as the first electrode 61.

The first light emitting unit 10 u includes a first semiconductor layer11, a second semiconductor layer 12, and a first light emitting layer10L. The first semiconductor layer 11 is separated from the firstelectrode 61 in a first direction D1.

For example, a direction perpendicular to a major surface 61 a of thefirst electrode 61 is taken as a Z-axis direction. One directionperpendicular to the Z-axis direction is taken as an X-axis direction. Adirection perpendicular to the Z-axis direction and the X-axis directionis taken as a Y-axis direction. The first direction D1 is parallel to,for example, the Z-axis direction.

The first semiconductor layer 11 includes a first semiconductor portion11 a and a second semiconductor portion 11 b. The second semiconductorportion 11 b is arranged with the first semiconductor portion 11 a in adirection crossing the first direction D1 (e.g., the Z-axis direction).For example, the second semiconductor portion 11 b is arranged with thefirst semiconductor portion 11 a in the X-Y plane. The firstsemiconductor layer 11 has a first conductivity type.

The second semiconductor layer 12 is provided between the secondsemiconductor portion 11 b and the first electrode 61. The secondsemiconductor layer 12 has a second conductivity type. The secondconductivity type is different from the first conductivity type.

The first light emitting layer 10L is provided between the secondsemiconductor portion 11 b and the second semiconductor layer 12. Thefirst light emitting layer 10L emits light (a first light) having afirst peak wavelength. The first light emitting unit 10 u is, forexample, an LED chip.

The second light emitting unit 20 u includes a third semiconductor layer23, a fourth semiconductor layer 24, and a second light emitting layer20L. The third semiconductor layer 23 is provided between the firstelectrode 61 and the first light emitting unit 10 u. The thirdsemiconductor layer 23 has a third conductivity type.

The fourth semiconductor layer 24 is provided between the thirdsemiconductor layer 23 and the first electrode 61. The fourthsemiconductor layer 24 is electrically connected with the firstelectrode 61. The fourth semiconductor layer 24 has a fourthconductivity type. The fourth conductivity type is different from thethird conductivity type.

The second light emitting layer 20L is provided between the thirdsemiconductor layer 23 and the fourth semiconductor layer 24. The secondlight emitting layer 20L emits light (a second light) having a secondpeak wavelength. The second light emitting unit 20 u is, for example, anLED chip.

For example, the second peak wavelength is different from the first peakwavelength. For example, the second peak wavelength is shorter than thefirst peak wavelength. For example, the second light is blue light; andthe first light is at least one selected from yellow light and redlight. The color (the peak wavelength) of the light is arbitrary.

The side wall of the first light emitting unit 10 u and the side wall ofthe second light emitting unit 20 u may have tapered configurations. Aseparate dielectric may be formed on at least one selected from the sidewall of the first light emitting layer 10L and the side wall of thesecond light emitting layer 20L.

For example, the first conductivity type is the same as the thirdconductivity type. For example, the second conductivity type is the sameas the fourth conductivity type. For example, the first conductivitytype and the third conductivity type are the n-type; and the secondconductivity type and the fourth conductivity type are the p-type. Inthe embodiment, the first conductivity type and the third conductivitytype may be the p-type; and the second conductivity type and the fourthconductivity type may be the n-type. In the embodiment, the first tofourth conductivity types are arbitrary. Hereinbelow, the case will bedescribed where the first conductivity type and the third conductivitytype are the n-type and the second conductivity type and the fourthconductivity type are the p-type.

These semiconductor layers include, for example, nitride semiconductors.For example, the first semiconductor layer 11 and the thirdsemiconductor layer 23 include, for example, an n-type GaN layer. Forexample, the second semiconductor layer 12 and the fourth semiconductorlayer 24 include, for example, a p-type GaN layer. The first lightemitting layer 10L and the second light emitting layer 20L include, forexample, a quantum well layer and a barrier layer. For example, aquantum well layer is provided between two barrier layers. The number ofquantum well layers may be one or more.

The first conductive layer 41 includes a first inter-layer portion 41 tand a first pad disposition portion 41 u. The first inter-layer portion41 t is provided between the first light emitting unit 10 u and thesecond light emitting unit 20 u. The first pad disposition portion 41 uis arranged with the first inter-layer portion 41 t in a directioncrossing the first direction D1. The first pad disposition portion 41 uis not provided between the first light emitting unit 10 u and thesecond light emitting unit 20 u. The first conductive layer 41 iselectrically connected with the third semiconductor layer 23.

In the example, the first conductive layer 41 further includes a firstextension portion 41 v. The first extension portion 41 v extends betweenthe first inter-layer portion 41 t and the first pad disposition portion41 u. The first extension portion 41 v connects the first inter-layerportion 41 t and the first pad disposition portion 41 u. The firstextension portion 41 v may be separated from the first inter-layerportion 41 t and the first pad disposition portion 41 u.

The first conductive layer 41 is, for example, light-shielding. Thefirst conductive layer 41 is, for example, light-reflective. The firstconductive layer 41 includes, for example, a metal. For example, a metalfilm of Al, Ni, Ti, etc., is used as the first conductive layer 41. Analloy may be used as the first conductive layer 41. A stacked film thatincludes multiple metal films may be used as the first conductive layer41.

At least a portion of the first conductive layer 41 may belight-transmissive. In such a case, the first conductive layer 41includes, for example, an oxide including at least one element selectedfrom the group consisting of In, Sn, Zn, and Ti. The first conductivelayer 41 includes, for example, ITO (Indium Tin Oxide), etc. The firstconductive layer 41 may include a thin film of a metal.

The first connection electrode 51 is electrically connected with thefirst semiconductor portion 11 a. The first connection electrode 51extends in the first direction D1. The first connection electrode 51 iselectrically connected with the third semiconductor layer 23. Forexample, the first connection electrode 51 is electrically connectedwith the first inter-layer portion 41 t.

In the example, the first connection electrode 51 includes a first metalunit 51 a and a second metal unit 51 b. The first metal unit 51 a isdisposed between the first semiconductor portion 11 a and at least aportion of the second metal unit 51 b. The first metal unit 51 a maycontact, for example, the first semiconductor portion 11 a. In theexample, the first connection electrode 51 further includes a thirdmetal unit 51 c. The third metal unit 51 c is provided between the firstmetal unit 51 a and the first semiconductor portion 11 a. The thirdmetal unit 51 c is, for example, the n-side electrode of the first lightemitting unit 10 u. The second metal unit 51 b is, for example, then-side electrode of the second light emitting unit 20 u.

The third metal unit 51 c includes a material having ohmic propertieswith the first semiconductor layer 11 and a low contact resistance. Thesecond metal unit 51 b may include, for example, a material having ohmicproperties with the third semiconductor layer 23 and a low contactresistance. The second metal unit 51 b may be, for example, connectedwith the first inter-layer portion 41 t with good adhesion. For example,the third metal unit 51 c and the second metal unit 51 b may include ametal film including at least one selected from the group consisting ofAl, Ti, Cu, Ag, and Ta. An alloy including the at least one selectedfrom the group may be used. A stacked film including multiple metalfilms of the at least one selected from the group may be used.

The first metal unit 51 a can electrically connect the second metal unit51 b and the third metal unit 51 c. For example, the first metal unit 51a may include a metal film including at least one selected from thegroup consisting of Al, Ti, Cu, Ag, Au, W, and Ni. An alloy includingthe at least one selected from the group may be used. A stacked filmincluding multiple metal films of the at least one selected from thegroup may be used.

The first dielectric layer 51 i is provided between the first connectionelectrode 51 and the second semiconductor layer 12 and between the firstconnection electrode 51 and the first light emitting layer 10L. Thefirst dielectric layer 51 i includes, for example, at least one selectedfrom metal oxide, metal nitride, and metal oxynitride. The firstdielectric layer 51 i includes, for example, silicon oxide.

The first pad 41 p is electrically connected with the thirdsemiconductor layer 23. For example, in the example, the first pad 41 pis electrically connected with the first pad disposition portion 41 u ofthe first conductive layer 41. In the example, the first conductivelayer 41 is disposed between the first pad 41 p and the second lightemitting unit 20 u. For example, the first conductive layer 41 isprovided on the second light emitting unit 20 u; and the first pad 41 pis provided on the first conductive layer 41 (on the first paddisposition portion 41 u).

The first semiconductor portion 11 a (i.e., the first semiconductorlayer 11) is electrically connected with the first pad 41 p via thefirst connection electrode 51 and the first conductive layer 41. Thethird semiconductor layer 23 is electrically connected with the firstpad 41 p via the first conductive layer 41. The first pad 41 p is, forexample, a pad for the first conductivity type (and the thirdconductivity type). For example, the first pad 41 p is used as an n-sidepad.

The second conductive layer 42 includes a second inter-layer portion 42t and a second pad disposition portion 42 u. The second inter-layerportion 42 t is provided between the first light emitting unit 10 u andthe second light emitting unit 20 u. The second pad disposition portion42 u is arranged with the second inter-layer portion 42 t in a directioncrossing the first direction D1. The second conductive layer 42 iselectrically connected with the second semiconductor layer 12.

The second pad 42 p is electrically connected with the secondsemiconductor layer 12. In the example, the second pad 42 p iselectrically connected with the second pad disposition portion 42 u. Thesecond conductive layer 42 is disposed between the second pad 42 p andthe second light emitting unit 20 u. In the example, the secondconductive layer 42 is provided on the second light emitting unit 20 u;and the second pad 42 p is provided on a portion (the second paddisposition portion 42 u) of the second conductive layer 42.

The second semiconductor layer 12 is electrically connected with thesecond pad 42 p via the second conductive layer 42. The second pad 42 pis used as a pad for the second conductivity type. The second pad 42 pis used as, for example, a p-side pad of the first light emitting unit10 u.

The first inter-light emitting unit dielectric layer 71 is providedbetween the first light emitting unit 10 u and the second light emittingunit 20 u. In the example, the first inter-light emitting unitdielectric layer 71 is further provided between the second conductivelayer 42 and the second light emitting unit 20 u. The first inter-lightemitting unit dielectric layer 71 is further provided between the firstlight emitting unit 10 u and the first conductive layer 41. The firstinter-light emitting unit dielectric layer 71 is further providedbetween the first conductive layer 41 and the second conductive layer42. The first inter-light emitting unit dielectric layer 71 islight-transmissive. The optical transmittance of the first inter-lightemitting unit dielectric layer 71 is higher than the opticaltransmittance of the first electrode 61. The optical reflectance of thefirst electrode 61 is higher than the optical reflectance of the firstinter-light emitting unit dielectric layer 71.

The first inter-light emitting unit dielectric layer 71 includes, forexample, at least one selected from metal oxide, metal nitride, andmetal oxynitride. The first inter-light emitting unit dielectric layer71 includes, for example, silicon oxide.

In the example, the second conductive layer 42 includes a firstlight-transmissive conductive unit 42 a and a first interconnect unit 42b. The first light-transmissive conductive unit 42 a is provided betweenthe first light emitting unit 10 u and the first inter-light emittingunit dielectric layer 71. The first light-transmissive conductive unit42 a is electrically connected with the second semiconductor layer 12.

The first light-transmissive conductive unit 42 a includes, for example,an oxide including at least one element selected from the groupconsisting of In, Sn, Zn, and Ti. The first light-transmissiveconductive unit 42 a includes, for example, ITO, etc. The firstlight-transmissive conductive unit 42 a may include a thin film of ametal.

The first interconnect unit 42 b is provided between, for example, thefirst light-transmissive conductive unit 42 a and the first inter-lightemitting unit dielectric layer 71. The first interconnect unit 42 b iselectrically connected with the first light-transmissive conductive unit42 a. The optical transmittance of the first interconnect unit 42 b islower than the optical transmittance of the first light-transmissiveconductive unit 42 a. A metal having a low resistivity is suited to thefirst interconnect unit 42 b. The first interconnect unit 42 b includes,for example, a metal film including at least one selected from the groupconsisting of Al, Au, Ag, and Cu, an alloy including the at least oneselected from the group, or a stacked film including multiple films ofthe at least one selected from the group.

In the example, at least a portion of the first light-transmissiveconductive unit 42 a is disposed between the second pad 42 p and thesecond light emitting unit 20 u. In other words, the second pad 42 p isdisposed on the first light-transmissive conductive unit 42 a. Asdescribed below, the second pad 42 p is provided on the firstinterconnect unit 42 b.

A support layer 66 c and a second electrode 62 are further provided inthe example. The first electrode 61 is disposed between the second lightemitting unit 20 u and the second electrode 62. The support layer 66 cis disposed between the first electrode 61 and the second electrode 62.In the example, the support layer 66 c is conductive. The secondelectrode 62 is electrically connected with the first electrode 61. Thesupport layer 66 c includes, for example, a Si substrate, etc. A metalsubstrate may be used as the support layer 66 c. For example, a metallayer (e.g., a plating metal layer), etc., may be used as the supportlayer 66 c. A composite of a combination of a resin and a metal may beused as the support layer 66 c. A composite of a combination of a resinand a ceramic may be used as the support layer 66 c.

A support layer-side dielectric layer 78 is further provided in theexample. The support layer-side dielectric layer 78 is provided along anouter edge 20Lr of the second light emitting unit 20 u between at leasta portion of the support layer 66 c and at least a portion of the secondlight emitting unit 20 u. The support layer-side dielectric layer 78includes, for example, at least one selected from metal oxide, metalnitride, and metal oxynitride. The support layer-side dielectric layer78 includes, for example, silicon oxide.

For example, a current is supplied to the second light emitting layer20L of the second light emitting unit 20 u via the first electrode 61 byapplying a voltage between the second electrode 62 and the first pad 41p. Thereby, the second light is emitted from the second light emittinglayer 20L. The second light is emitted to the outside by passing throughthe first inter-light emitting unit dielectric layer 71 and the firstlight emitting unit 10 u.

For example, a current is supplied to the first light emitting layer 10Lof the first light emitting unit 10 u by applying a voltage between thesecond pad 42 p and the first pad 41 p. Thereby, the first light isemitted from the first light emitting layer 10L. The first light isemitted to the outside from the first semiconductor layer 11 side.

In the semiconductor light emitting element 110, the light is emitted tothe outside by passing through the first light emitting unit 10 u. Forexample, the first light emitting unit 10 u has a surface 11 u. Thesurface 11 u is a surface on the side opposite to the second lightemitting unit 20 u. The surface 11 u is, for example, the upper surface.The surface 11 u is used as a surface on the light extraction side ofthe semiconductor light emitting element 110.

As illustrated in FIG. 1A to FIG. 1C, a light-transmissive conductivelayer 11 el may be provided on the surface 11 u. The first semiconductorlayer 11 is disposed between the conductive layer 11 el and the firstlight emitting layer 10L. The conductive layer 11 el is used as, forexample, the n-side electrode of the first light emitting unit 10 u. Byproviding the conductive layer 11 el, the current spreading of the firstsemiconductor layer 11 of the first light emitting unit 10 u isincreased. Thereby, the operating voltage decreases; and the luminousefficiency increases. When projected onto the X-Y plane, at least aportion of the conductive layer 11 el may overlap at least a portion ofat least one selected from the first conductive layer 41 and the firstinterconnect unit 42 b. Thereby, color breakup is suppressed; and theabsorption of the emitted light by the conductive layer 11 el issuppressed. Thereby, uneven color can be reduced; and the lightextraction efficiency can be increased. The conductive layer 11 el maybe light-transmissive. The conductive layer 11 el may be provided asnecessary and may be omitted.

As shown in FIG. 1A, the first pad 41 p is separated from the second pad42 p. For example, when projected onto a plane (the X-Y plane)perpendicular to the first direction D1, the first pad 41 p does notoverlap the second pad 42 p.

In the semiconductor light emitting element 110 according to theembodiment, the first pad 41 p is used as both the n-side pad of thefirst light emitting unit 10 u and the n-side pad of the second lightemitting unit 20 u. The first pad 41 p is shared by the two lightemitting units. In the semiconductor light emitting element 110, thereare few interconnects that have low optical transmittance. Thereby, ahigh light extraction efficiency is obtained. According to thesemiconductor light emitting element 110, a stacked semiconductor lightemitting element having a high efficiency can be provided.

For example, in a stacked semiconductor light emitting element (e.g., amulticolor light emission LED) in which the light emission iscontrollable independently, current is injected independently to each ofthe multiple light emitting layers (e.g., the multiple LED chips). Forexample, two electrodes of the n-side electrode and the p-side electrodeare provided in one LED. Therefore, in the stacked LED, the number ofconduction paths (e.g., pads, bumps, etc.) increases proportionally totwice the number of stacks. As the conduction paths increase, thesurface area of the light emitting region decreases; and the efficiencydecreases. Further, the assembly processes become complex.

In the stacked semiconductor light emitting element of the embodiment,the number of conduction paths (e.g., pads, bumps, etc.) can be reduced.

In the embodiment, the first pad 41 p is, for example, a common n-sidepad. The second pad 42 p is, for example, the p-side pad of the lightemitting unit of the upper side. The first connection electrode 51 isthe n-side electrode of the light emitting unit of the upper side and isa connection electrode. The first light-transmissive conductive unit 42a of the second conductive layer 42 is, for example, the p-sideelectrode of the light emitting unit of the upper side. The firstinterconnect unit 42 b of the second conductive layer 42 is, forexample, an interconnect electrode of the light emitting unit of theupper side. The first conductive layer 41 functions as, for example, then-side electrode of the light emitting unit of the lower side, theinterconnect electrode of the light emitting unit of the lower side, andthe interconnect electrode of the light emitting unit of the upper side.Multiple first connection electrodes 51 may be provided. In such a case,for example, because the current spreading increases, the operatingvoltage decreases; and the luminous efficiency increases.

In the embodiment, a transparent bonding member (e.g., the firstinter-light emitting unit dielectric layer 71) is provided betweenmultiple light emitting units (e.g., the LED chips). Then, the lightemitting unit (e.g., the first light emitting unit 10 u) of the upperside has a laterally conducting structure. The n-side electrode (e.g.,the first connection electrode 51) of the light emitting unit of theupper side pierces the transparent bonding member to be electricallyconnected with the n-type semiconductor layer (the third semiconductorlayer 23) of the light emitting unit (the second light emitting unit 20u) of the lower side. In the embodiment, a dielectric (the firstinter-light emitting unit dielectric layer 71) is provided between thelight emitting unit of the upper side and the light emitting unit of thelower side. The n-side electrode of the light emitting unit of the upperside pierces the dielectric to be electrically connected with the n-typesemiconductor of the light emitting unit of the lower side.

Thereby, the number of conduction paths (the first electrode 61, thefirst pad 41 p, and the second pad 42 p) is three when the number ofstacks is two. In other words, the number of conduction paths decreases.Thereby, the light emitting region widens; and high efficiency isobtained. Further, the assembly processes are simplified. According tothe embodiment, the light extraction efficiency increases. Further, theinterconnect resistance can be reduced; and the operating voltagedecreases. The cost can be reduced. The yield can be increased.

In the embodiment, for example, the current is supplied to the n-sideelectrode of the light emitting unit (e.g., the first light emittingunit 10 u) of the upper side from the n-side pad of the light emittingunit (the second light emitting unit 20 u) of the lower side. The n-sideelectrode (e.g., the first conductive layer 41) and the n-typesemiconductor layer (the third semiconductor layer 23) of the lightemitting unit (the second light emitting unit 20 u) of the lower sidefunction as the current spreading layers of the light emitting unit (thefirst light emitting unit 10 u) of the upper side. Thereby, the luminousefficiency can be increased. Also, the number of interconnects can bereduced.

FIG. 2A to FIG. 2D are schematic views illustrating the semiconductorlight emitting element according to the first embodiment.

FIG. 2A is a cross-sectional view of the same cross section as FIG. 1C.FIG. 2B to FIG. 2D are schematic see-through plan views corresponding toregions R1 to R3 shown in FIG. 2A. The regions R1 to R3 are regionsparallel to the X-Y plane. The region R1 is the region including thefirst pad 41 p and the first conductive layer 41. The region R2 is theregion including the first light-transmissive conductive unit 42 a andthe first interconnect unit 42 b. The region R3 is the region includingthe second pad 42 p and the first light-transmissive conductive unit 42a.

As shown in FIG. 2B, the semiconductor light emitting element 110 has asubstantially rectangular planar configuration. In the example, thefirst conductive layer 41 is provided along the sides of the rectanglein the region R1. The first connection electrode 51 and the first pad 41p are connected by the first conductive layer 41. The portion around thefirst connection electrode 51 is used as the first dielectric layer 51i. The remaining portion is used as the first inter-light emitting unitdielectric layer 71.

As shown in FIG. 2C, the first light-transmissive conductive unit 42 aand the first interconnect unit 42 b are provided in the region R2. Thefirst light-transmissive conductive unit 42 a and the first interconnectunit 42 b are electrically connected with each other. The firstdielectric layer 51 i is provided between the first connection electrode51 and the first light-transmissive conductive unit 42 a and between thefirst connection electrode 51 and the first interconnect unit 42 b.These conductive units are insulated from each other.

As shown in FIG. 2B and FIG. 2C, at least a portion of the firstconductive layer 41 and at least a portion of the first interconnectunit 42 b overlap each other when projected onto the X-Y plane. Forexample, when projected onto the X-Y plane, at least a portion of thefirst extension portion 41 v of the first conductive layer 41 and atleast a portion of the first interconnect unit 42 b overlap each other.

As shown in FIG. 2D, the first light-transmissive conductive unit 42 aand the second pad 42 p are provided in the region R3. The firstlight-transmissive conductive unit 42 a and the second pad 42 p areelectrically connected with each other. The first dielectric layer 51 iis provided between the first connection electrode 51 and the firstlight-transmissive conductive unit 42 a. These conductive units areinsulated from each other.

According to the semiconductor light emitting element 110, a stackedsemiconductor light emitting element having a high efficiency can beprovided. In the semiconductor light emitting element 110, variousmodifications of the pattern arrangements of the components arepossible.

An example of a method for manufacturing the semiconductor lightemitting element 110 will now be described.

FIG. 3A to FIG. 3C are schematic views illustrating the method formanufacturing the semiconductor light emitting element according to thefirst embodiment.

First, an example of the method for making the second light emittingunit 20 u will be described.

The third semiconductor layer 23, the second light emitting layer 20L,and the fourth semiconductor layer 24 are formed in this order by MOCVDon a growth substrate (e.g., a sapphire substrate, a Si substrate,etc.). A stacked body (a crystal layer) that includes thesesemiconductor layers is formed. The crystal layer is a portion of asemiconductor wafer. At this time, a buffer layer may be formed on thegrowth substrate; and the third semiconductor layer 23 may be formed onthe buffer layer. The material and plane orientation of the growthsubstrate are arbitrary.

For example, a SiO₂ film is formed on the crystal layer (i.e., on thefourth semiconductor layer 24). The thickness of the SiO₂ film is, forexample, 400 nanometers (nm).

For example, a Ag layer is formed on the fourth semiconductor layer 24by lift-off. The thickness of the Ag layer is, for example, 200 nm. Forexample, heat treatment is performed. For example, the conditions of theheat treatment are between 300° C. and 800° C. in oxygen. The Ag layeris used as at least a portion of the first electrode 61.

A metal layer is formed on the entire fourth semiconductor layer 24 andthe Ag layer. The metal layer includes a barrier metal and a metal filmfor solder bonding. For example, the layers of TiW 50 nm/Pt 100 nm/TiW50 nm/Pt 100 nm/Ti 100 nm/Au 50 nm are formed. The metal layer may beincluded in the first electrode 61 for convenience.

The support layer 66 c is prepared. The support layer 66 c includes, forexample, a Si substrate. A solder layer of, for example, Au—Sn isprovided on the surface of the Si substrate. The thickness of the solderlayer is, for example, about 2000 nm. The solder layer and the firstelectrode 61 (e.g., the metal layer recited above) are bonded by causingthe solder layer and the semiconductor wafer recited above to opposeeach other. For example, the bonding is performed at a temperature ofabout 280° C.

The growth substrate is removed. For example, in the case where asapphire substrate is used as the growth substrate, for example, LLO(Laser Lift Off) is used. In the case where a Si substrate is used asthe growth substrate, at least one selected from polishing, dry etching,and wet etching is used.

The buffer layer recited above is exposed by removing the growthsubstrate. The third semiconductor layer 23 is exposed by removing theexposed buffer layer.

The first conductive layer 41 (the interconnect electrode) is formed onthe surface of the exposed third semiconductor layer 23. In such a case,for example, lift-off is used. For example, a stacked film (having atotal thickness of 500 nm) of Al/Ni/Au is formed as the first conductivelayer 41.

The first conductive layer 41 includes a pad region (the first paddisposition portion 41 u) where the pad is subsequently formed, aninterconnect electrode (the first extension portion 41 v) for spreadingthe current, and a connection region (the first inter-layer portion 41t) where the first connection electrode 51 is subsequently formed.

The configuration of the pad region (the first pad disposition portion41 u) is, for example, a rectangle, an ellipse, a fan-likeconfiguration, or a combination of such shapes. The size (the length ina direction perpendicular to the Z-axis direction) of the pad region is,for example, not more than 100 μm. The line width of the firstconductive layer 41 (the width of the first extension portion 41 v) is,for example, 10 μm (e.g., not less than 5 μm and not more than 50 μm).

A portion of the first conductive layer 41 may be provided as necessaryand may be omitted. For example, in the case where the chip size issmall, the first extension portion 41 v of the first conductive layer 41may not be provided. In such a case, the first inter-layer portion 41 t(the portion directly under the first connection electrode 51 describedbelow) of the first conductive layer 41 and the first pad dispositionportion 41 u (the pad region) of the first conductive layer 41 areprovided.

It is favorable for the thickness of the first conductive layer 41 tobe, for example, not less than 10 nm and not more than 10000 nm. It ismore favorable for the thickness of the first conductive layer 41 to be,for example, not less than 50 nm and not more than 1000 nm.

In the case where the thickness of the first conductive layer 41 isthin, the difference in levels when planarizing in the CMP processdescribed below becomes small. Thereby, the necessary polishing amountdecreases. The thickness of the first inter-light emitting unitdielectric layer 71 described below can be thinner; and the filmformation time and the CMP processing time can be reduced. Thereby, forexample, the cost decreases. In the case where the thickness of thefirst conductive layer 41 is thick, the interconnect resistance of thefirst conductive layer 41 (the first extension portion 41 v) decreases;and the spread of the current is easy. Thereby, the effective lightemitting region increases; the luminous efficiency increases; and theoperating voltage decreases.

A Cu layer that is used to form an electrode (the second metal unit 51b) for connecting is formed by lift-off in the region including the topof the first inter-layer portion 41 t. The thickness of the Cu layer is,for example, 200 nm.

The configuration of the second metal unit 51 b is, for example, arectangle, a polygon, an ellipse (including a circle), a fan-likeconfiguration, or a combination of these shapes. It is favorable for thethickness of the second metal unit 51 b to be, for example, not lessthan 10 nm and not more than 10000 nm. It is more favorable for thethickness of the second metal unit 51 b to be not less than 50 nm andnot more than 500 nm. The second metal unit 51 b is designed such thatthe second metal unit 51 b can be exposed in the CMP process describedbelow. It is favorable for the size (the length in a directionperpendicular to the Z-axis direction) of the second metal unit 51 b tobe not less than 1 μM and not more than 100 μm. It is more favorable forthe size of the second metal unit 51 b to be not less than 5 μm and notmore than 20 μm.

In the case where the second metal unit 51 b is small, the lightextraction efficiency increases because the effective cross-sectionalarea for the emitted light decreases. In the case where the second metalunit 51 b is large, the requirements on the alignment precision in thebonding process described below can be relaxed; and the current densitywhen a large current flows can be suppressed to be low. Thereby, forexample, the yield increases; the cost decreases; and the life islonger.

The second metal unit 51 b may include, for example, a film of oneselected from Al, Ag, Ni, Cu, W, Ti, and Au or a stacked film includingat least one of the films.

The second metal unit 51 b may include a metal having a low resistivity.Thereby, a large current is caused to flow. The second metal unit 51 bmay include a metal having a high reflectance to the emitted light.Thereby, the light extraction efficiency increases. The number of thesecond metal units 51 b is, for example, the same as the number of theconnection electrodes (the first metal units 51 a) of the first lightemitting unit 10 u described below. The position of the second metalunit 51 b in the X-Y plane overlaps the position of the first metal unit51 a in the X-Y plane.

A light-transmissive insulating layer is formed to cover the secondmetal unit 51 b and the first conductive layer 41. The insulating layeris used to form a portion of the first inter-light emitting unitdielectric layer 71. The insulating layer is, for example, a SiO₂ film.The thickness of the SiO₂ film is, for example, not less than 100 nm andnot more than 10000 nm. The SiO₂ film is formed by, for example, ECRsputtering or plasma CVD. Thereby, for example, high-quality filmproperties are obtained at a low temperature. For example, in the casewhere plasma CVD is used, the occurrence of voids in structures having alarge difference in levels can be suppressed because the coverage isgood.

The connection electrode (the second metal unit 51 b) recited above maybe formed after the light-transmissive insulating layer (the SiO₂ film)is formed. The method for forming the connection electrode (the secondmetal unit 51 b) may be, for example, lift-off combined with vapordeposition, sputtering, CVD, plating, or a combination of these methods.

Planarizing is performed by CMP processing. Thereby, the second metalunit 51 b is exposed. In the case where the difference in levels islarge, the SiO₂ film recited above is set to be thick due to theplanarizing by CMP processing. The thickness of the SiO₂ film is set tobe not less than three times the thickness of the difference in levels.

For example, a pseudo-flat state may be made prior to the CMP processingby reducing the difference in levels of the SiO₂ film by dry etching,etc. Thereby, the polishing amount (thickness) necessary in theplanarizing can be reduced.

A slurry for which the etching rates of the second metal unit 51 b andthe SiO₂ film are adjusted may be used. Thereby, for example, the secondmetal unit 51 b and the SiO₂ film can be planarized simultaneously inthe CMP processing.

Thus, the structural body (the second stacked body 20 us, i.e., thesecond semiconductor wafer 20 uw) illustrated in FIG. 3A is formed. Thestructural body includes the second light emitting unit 20 u. Forexample, a SiO₂ film (a second dielectric film 71 b) and the secondmetal unit 51 b recited above are provided on the upper surface of thestructural body.

The second metal unit 51 b may be caused to slightly protrude bypolishing slightly using a slurry having a high etching rate for thematerial of the first conductive layer 41 after the CMP processingrecited above. Similar processing also may be performed for the firstmetal unit 51 a of the first light emitting unit 10 u described below.Thereby, the protruding second metal unit 51 b and the protruding firstmetal unit 51 a are bonded to contact each other. Because the metalshave ductility, the metals are mashed when subjected to the compressivestress; and the second metal unit 51 b and the first metal unit 51 a canbe connected with high yield while bonding the two SiO₂ films.

The method for connecting the second metal unit 51 b and the first metalunit 51 a may include methods utilizing the high coefficient of thermalexpansion of the metals. In other words, these metal units are bondedafter the CMP processing; and heat treatment at about 350° C. isperformed. Thereby, thermal expansion of the second metal unit 51 b andthe first metal unit 51 a occurs; and more reliable conduction isobtained.

An example of a method for making the first light emitting unit 10 uwill now be described.

The first semiconductor layer 11, the first light emitting layer 10L,and the second semiconductor layer 12 are formed in this order by, forexample, MOCVD on a growth substrate (a growth substrate 10 sillustrated in FIG. 3B). In FIG. 3A, up and down in the drawing areshown as being reversed from up and down when forming the semiconductorlayers. A stacked body (a crystal layer) that includes thesesemiconductor layers is formed. The crystal layer is a portion of asemiconductor wafer. At this time, a buffer layer may be formed on thegrowth substrate; and the first semiconductor layer 11 may be formed onthe buffer layer. The growth substrate 10 s includes, for example, asapphire substrate, a Si substrate, etc. The material and planeorientation of the growth substrate 10 s are arbitrary.

The first peak wavelength of the first light emitted from the firstlight emitting layer 10L may be longer than or shorter than the secondpeak wavelength of the second light emitted from the second lightemitting layer 20L. In the case where the first peak wavelength islonger than the second peak wavelength, the absorption of the light bythe first light emitting layer 10L is suppressed. Thereby, a high lightextraction efficiency is obtained.

A light-transmissive electrode (e.g., ITO) that is used to form thefirst light-transmissive conductive unit 42 a is formed on the crystallayer of the first light emitting unit 10 u (on the second semiconductorlayer 12). The thickness of the light-transmissive electrode is, forexample, 400 nm (e.g., not less than 100 nm and not more than 800 nm).For example, heat treatment is performed at 700° C. in nitrogen.Thereby, the first light-transmissive conductive unit 42 a is formed.

A stacked film of Ti/Pt/Au that is used to form the first interconnectunit 42 b is formed by, for example, lift-off on the firstlight-transmissive conductive unit 42 a. The total thickness of thestacked film is, for example, 500 nm (e.g., not less than 200 nm and notmore than 800 nm). The first interconnect unit 42 b is used to form theinterconnect electrode of the first light emitting unit 10 u for thesecond semiconductor layer 12.

The resistivity of the first light-transmissive conductive unit 42 a isrelatively high. By providing the first interconnect unit 42 b, thecurrent spreading properties can be improved. Thereby, the current canbe spread in a wide region of the second semiconductor layer 12. Theline width of the first interconnect unit 42 b is, for example, 10 μm(e.g., not less than 5 μm and not more than 30 μm). In the case wherethe chip size is small, the first interconnect unit 42 b may not beprovided.

It is favorable for the thickness of the first interconnect unit 42 b tobe, for example, not less than 10 nm and not more than 10000 nm. It ismore favorable for the thickness of the first interconnect unit 42 b tobe not less than 50 nm and not more than 1000 nm. In the case where thethickness of the first interconnect unit 42 b is thin, the difference inlevels is small and the necessary polishing amount is low whenplanarizing in the CMP process described below. Thereby, the thicknessof the first inter-light emitting unit dielectric layer 71 describedbelow can be thin. The processing time of the CMP processing can bereduced. Thereby, the cost can be reduced. In the case where thethickness of the first interconnect unit 42 b is thick, the interconnectresistance of the first interconnect unit 42 b can be reduced; and thecurrent spreading increases. Thereby, the effective light emittingregion increases; the luminous efficiency increases; and the operatingvoltage decreases.

For example, a portion of the first light-transmissive conductive unit42 a, the second semiconductor layer 12, and the first light emittinglayer 10L is removed by dry etching. The first semiconductor layer 11 isexposed at the removed portion. The exposed portion is used as the firstsemiconductor portion 11 a. The depth of the hole made by the removalis, for example, 1000 nm (e.g., not less than 600 nm not more than 1500nm). The wall surface of the hole may be perpendicular (perpendicular tothe X-Y plane). The wall surface of the hole may have a taperedconfiguration. In the case of being perpendicular, the surface areaoccupied by the hole can be small; and the light emission surface areacan be increased. In the case of the tapered configuration, the coverageof the insulating unit described below improves.

It is favorable for the width (the length in a direction perpendicularto the Z-axis direction) of the hole to be, for example, not less than 1μM and not more than 100 μm. It is more favorable for the width of thehole to be, for example, not less than 5 μm and not more than 20 μm. Inthe case where the width of the hole is narrow, the surface area of thefirst light emitting layer 10L can be increased. Thereby, the lightemitting region can be enlarged; the luminous efficiency increases; andthe operating voltage can be reduced. In the case where the width of thehole is wide, the size of the connection electrode (the first connectionelectrode 51) described below can be large.

In the case where the number of holes is low, the surface area of thefirst light emitting layer 10L can be increased. Thereby, the lightemitting region can be enlarged. In the case where the number of holesis high, multiple n-side electrodes (e.g., the first metal units 51 a)described below can be disposed over the entire element. Thereby, thecurrent can be injected uniformly into the first light emitting layer10L. Thereby, the luminous efficiency increases; and the operatingvoltage decreases. The emitted light that is wave-guided through thecrystal layer of the first light emitting unit 10 u can be scattered orreflected at the holes. Thereby, the probability of extracting, to theoutside, the emitted light that is trapped inside the crystal layerincreases. Thereby, the light extraction efficiency increases.

For example, a SiO₂ film is formed as a dielectric layer over the entirefirst light-transmissive conductive unit 42 a, the first interconnectunit 42 b, and the exposed crystal layer. The thickness of the SiO₂ filmis, for example, about 400 nm (e.g., not less than 200 nm and not morethan 800 nm). The SiO₂ film that is provided on the side surface of thehole is used as an insulating unit that insulates the secondsemiconductor layer 12 from the first semiconductor layer 11. In otherwords, the SiO₂ film that is provided on the side surface of the hole isused to form at least a portion of the first dielectric layer 51 i. TheSiO₂ film that is formed on the bottom of the hole is removedsubsequently. The remaining region of the SiO₂ film is used to form aportion of the first inter-light emitting unit dielectric layer 71.

The SiO₂ film that is formed on the bottom of the hole is removed toexpose the first semiconductor layer 11 at the bottom of the hole. Astacked film of Al/Ti that is used to form the third metal unit 51 c(the n-side electrode) is formed on the exposed first semiconductorlayer 11. The thickness of the stacked film is, for example, about 200nm (e.g., not less than 100 nm and not more than 400 nm). It isfavorable for the thickness of the third metal unit 51 c to be not lessthan 10 nm and not more than 10000 nm. It is more favorable for thethickness of the third metal unit 51 c to be not less than 50 nm and notmore than 1000 nm. The third metal unit 51 c has an ohmic contact withthe first semiconductor layer 11. The third metal unit 51 c may be asingle-layer film or may be a stacked film of different multiple metalfilms.

For example, an Al film is formed to fill the hole. The Al film is usedto form a portion of the first connection electrode 51. The Al film isused to form a connection electrode (the first metal unit 51 a) on thefirst light emitting unit 10 u side. The connection electrode may beformed by, for example, lift-off combined with vapor deposition,sputtering, CVD, plating, or a combination of these methods. Forexample, a Cu layer may be formed as the connection electrode byelectroless plating. In such a case, for example, a Cu film or a Au filmmay be formed inside the hole as a seed layer. Seed layer enhancementmay be performed for the seed layer of the plating. In other words, forexample, a W film may be formed by, for example, CVD.

The connection electrode (the first metal unit 51 a) also may be used asthe third metal unit 51 c (the n-side electrode of the first lightemitting unit 10 u). In other words, the third metal unit 51 c may beomitted. The shape, number, and size of the connection electrode (thefirst metal unit 51 a) on the first light emitting unit 10 u sidecorrespond to the shape, number, and size of the connection electrode(the second metal unit 51 b) on the second light emitting unit 20 uside.

The connection electrode (the first metal unit 51 a) includes, forexample, a film of at least one selected from Cu, Ag, Ni, Ti, W, and Auor a stacked film of multiple films including at least one selected fromthese films. A metal having a low resistivity may be used as theconnection electrode (the first metal unit 51 a). Thereby, a largecurrent can be caused to flow. A metal having a high reflectance to theemitted light may be used as the connection electrode (the first metalunit 51 a). Thereby, the light extraction efficiency can be increased.

A light-transmissive insulating layer (e.g., a SiO₂ film) is formed tocover the connection electrode (the first metal unit 51 a). Theinsulating layer (the SiO₂ film) is used to form, for example, anotherportion of the first inter-light emitting unit dielectric layer 71. Thethickness of the insulating layer is, for example, not less than 100 nmand not more than 10000 nm. The insulating layer may be formed by, forexample, ECR sputtering or plasma CVD. Thereby, for example,high-quality film properties are obtained at a low temperature. Forexample, because a film formed by plasma CVD has good coverage, theoccurrence of voids in structures having a large difference in levelscan be suppressed.

The connection electrode (the first metal unit 51 a) recited above maybe formed after the light-transmissive insulating layer recited above isformed. The connection electrode (the first metal unit 51 a) is formedby, for example, lift-off combined with vapor deposition, sputtering,CVD, plating, or a combination of these methods.

The light-transmissive insulating layer (e.g., the SiO₂ film) isplanarized by CMP processing. Thereby, the connection electrode (thefirst metal unit 51 a) is exposed. In the case where the difference inlevels is large, the thickness of the SiO₂ film is set to be thickbecause of the planarizing by CMP processing. The thickness of the SiO₂film is set to be, for example, not less than three times the differencein levels. A pseudo-flat state may be made by reducing the difference inlevels of the SiO₂ film by dry etching, etc., prior to the CMPprocessing. Thereby, the polishing amount (the thickness) necessary inthe planarizing can be small.

Thereby, the structural body (the first stacked body 10 us, i.e., thefirst semiconductor wafer 10 uw) illustrated in FIG. 3B is formed. Thestructural body includes the first light emitting unit 10 u. Forexample, the SiO₂ film (a first dielectric film 71 a) and the firstmetal unit 51 a recited above are provided on the surface (the lowersurface) of the structural body.

The first stacked body 10 us and the second stacked body 20 us recitedabove are connected, for example, as follows.

The SiO₂ film (the first dielectric film 71 a) of the first stacked body10 us and the SiO₂ film (the second dielectric film 71 b) of the secondstacked body 20 us that have been subjected to the CMP processing arebonded by, for example, direct bonding. For example, plasma cleaningusing an oxygen atmosphere is performed in a vacuum.

As shown in FIG. 3C, the SiO₂ film (the first dielectric film 71 a) ofthe first semiconductor wafer 10 uw of the first stacked body 10 us andthe SiO₂ film (the second dielectric film 71 b) of the secondsemiconductor wafer 20 uw of the second stacked body 20 us are caused tooppose each other and are brought into contact. Then, for example, apressure of 1 kN is applied at a temperature of 150° C. Thereby, thefirst semiconductor wafer 10 uw of the first stacked body 10 us and thesecond semiconductor wafer 20 uw of the second stacked body 20 us arebonded to each other. At this time, alignment is performed such that thefirst metal unit 51 a and the second metal unit 51 b are electricallyconnected.

The growth substrate 10 s of the first light emitting unit 10 u isremoved. In the case where the growth substrate 10 s is a sapphiresubstrate, LLO is used. In the case where the growth substrate 10 s is aSi substrate, at least one selected from polishing, dry etching, and wetetching is used. Thereby, the crystal layer of the first light emittingunit 10 u is exposed. For example, the buffer layer of the first lightemitting unit 10 u is exposed. The buffer layer is removed by dryetching. Thereby, the first semiconductor layer 11 is exposed.

Then, element separation is performed.

For example, a portion of the crystal layer of the first light emittingunit 10 u is removed by dry etching. Thereby, the firstlight-transmissive conductive unit 42 a is exposed.

Dry etching, wet etching, etc., is performed to remove a portion of theexposed first light-transmissive conductive unit 42 a and remove aportion of the exposed first inter-light emitting unit dielectric layer71. Thereby, a crystal layer (e.g., the third semiconductor layer 23) ofthe second light emitting unit 20 u and a pad region (the first paddisposition portion 41 u) of the n-side electrode (the first conductivelayer 41) of the second light emitting unit 20 u are exposed.

The SiO₂ film (the support layer-side dielectric layer 78) contactingthe fourth semiconductor layer 24 is exposed by removing a portion ofthe exposed crystal layer of the second light emitting unit 20 u by dryetching, wet etching, etc.

A not-shown insulating layer (e.g., a SiO₂ film) is formed on the entiresurface of the support layer 66 c on the light emitting unit side. Thethickness of the insulating layer is, for example, about 400 nm (e.g.,not less than 200 nm and not more than 800 nm). The insulating layer isformed by, for example, CVD. The insulating layer is used as apassivation film of the first light emitting unit 10 u and the secondlight emitting unit 20 u. The insulating layer covers the side surfaceof the first light emitting layer 10L and covers the side surface of thesecond light emitting layer 20L.

For example, a stacked film of Ti/Pt/Au is formed by, for example,spacer lift-off on the exposed pad region (the first pad dispositionportion 41 u of the first conductive layer 41) and on the exposed p-sideelectrode (the second pad disposition portion 42 u of the secondconductive layer 42). The thickness of the stacked film is, for example,about 500 nm (e.g., not less than 200 nm and not more than 800 nm).Thereby, the common n-side electrode pad (the first pad 41 p) of thefirst light emitting unit 10 u and the second light emitting unit 20 uand the p-side electrode pad (the second pad 42 p) of the first lightemitting unit 10 u are formed.

As described above, the first conductive layer 41 has a portionoverlapping the first interconnect unit 42 b when projected onto the X-Yplane. The first interconnect unit 42 b has a portion overlapping thefirst conductive layer 41 when projected onto the X-Y plane. The lightemitted from the light emitting layers is shielded by the firstconductive layer 41 and the first interconnect unit 42 b. The regionwhere the emitted light is shielded can be small because at least aportion of the first conductive layer 41 and at least a portion of thefirst interconnect unit 42 b overlap each other. Thereby, the lightextraction efficiency increases. Further, uneven color can be reduced.

Subsequently, the second electrode 62 is formed. In other words, forexample, the support layer 66 c is polished; and the thickness of thesupport layer 66 c is caused to be thin, e.g., about 150 μm. Forexample, a stacked film of Ti/Pt/Au that is used to form the secondelectrode 62 is formed on the polishing surface. The thickness of thestacked film is, for example, about 500 nm (e.g., not less than 200 nmand not more than 800 nm). Thereby, the second electrode 62 that iselectrically connected with the first electrode 61 is formed.

The second electrode 62 may be formed on the first electrode 61. In sucha case, for example, the first electrode 61 also may be exposed whenexposing the support layer-side dielectric layer 78; and the secondelectrode 62 may be formed simultaneously on the first electrode 61 whenforming the first pad 41 p and the second pad 42 p.

The second electrode 62 may be formed on the first electrode 61. In sucha case, for example, a portion of the first electrode 61 also may beexposed when exposing the support layer-side dielectric layer 78; andthe second electrode 62 may be formed simultaneously on the firstelectrode 61 when forming the first pad 41 p and the second pad 42 p.

Subsequently, singulation is performed by dicing, etc. Thereby, thesemiconductor light emitting element 110 is formed.

According to the semiconductor light emitting element 110, a stackedsemiconductor light emitting element having a high efficiency can beprovided.

On the other hand, a reference example of a multicolor light emissionLED may be considered in which multiple LED chips are stacked in anassembly process. In the reference example, a p-side interconnect and ann-side interconnect are provided for each of the LED chips. In the casewhere two LED chips are stacked, four interconnects are necessary. Inthe case where three LED chips are stacked, six interconnects arenecessary. Therefore, the light extraction efficiency decreases due tothe surface area of interconnects that do not contribute to the lightextraction. Moreover, due to the complex assembly process, the yield islow; and the cost is high.

In the reference example, the light is extracted in different directionson the lower side and upper side in the case where the substrate (thegrowth substrate or the support substrate) or the electrode (in the caseof a nitride semiconductor, the p-side electrode) covering substantiallythe entire surface of the LED chip disposed on the upper side is notlight-transmissive for the light emitted from the LED chip disposed onthe lower side (the package side). Therefore, color breakup occurs.Color breakup is, for example, a phenomenon in which the color of theemitted light changes with the viewing angle direction. Further, thelight extraction efficiency of the LED chip disposed on the lower sidemarkedly decreases because the major surface is covered with asubstrate.

In the reference example, even in the case where the substrate islight-transmissive, it is necessary to expose the bonding pads.Therefore, it is necessary to stack LED chips having different chipsizes; and color breakup occurs. Moreover, it is necessary to use a widealignment margin because the alignment precision in the assembly processis worse than the alignment precision in the photolithography process.Therefore, color breakup occurs more easily. Then, the light extractionefficiency decreases further. The yield decreases more easily.

Moreover, in the reference example, the thickness of the substratenormally is not less than 100 μm. Therefore, for the LED chip disposedon the upper side, the heat dissipation is poor; and the life is short.In the reference example, stacking is performed for each chip.Therefore, manufacturing takes time; and the cost increases.

In the semiconductor light emitting element 110 according to theembodiment, it is unnecessary to form an electrode on the surface on thelight extraction side. Therefore, the light extraction efficiency ishigh. The interconnects can be omitted; and a high light extractionefficiency is obtained. Because a complex assembly process is not used,the yield is high; and the cost can be reduced. In the embodiment, colorbreakup can be suppressed. In the embodiment, because it is unnecessaryto provide a substrate in the light emitting unit on the upper side, theheat dissipation is good; and a long life is obtained. In theembodiment, because multiple light emitting units are stacked in thewafer state, the manufacturing is simple; and the cost can be reduced.

FIG. 4 is a schematic cross-sectional view illustrating anothersemiconductor light emitting element according to the first embodiment.

FIG. 4 is a cross-sectional view corresponding to a line B1-B2 crosssection of FIG. 1A.

In the semiconductor light emitting element 111 according to theembodiment as shown in FIG. 4, the planar configuration of the firstlight-transmissive conductive unit 42 a is, for example, substantiallythe same as the planar configuration of the first light emitting unit 10u. Also, the second pad 42 p is provided on the first interconnect unit42 b.

In other words, at least a portion of the first interconnect unit 42 bis disposed between the second pad 42 p and the second light emittingunit 20 u.

In the semiconductor light emitting element 111 as well, a stackedsemiconductor light emitting element having a high efficiency can beprovided.

FIG. 5A and FIG. 5B are schematic cross-sectional views illustratingother semiconductor light emitting elements according to the firstembodiment.

These drawings illustrate a portion of the first light emitting unit 10u.

As shown in FIG. 5A, the first light emitting unit 10 u includes thesurface 11 u on the side opposite to the second light emitting unit 20u. The surface 11 u is a surface on the light extraction side of thesemiconductor light emitting element. In the semiconductor lightemitting element 110 a, an unevenness 11 pd is provided in the surface11 u. In the example, the unevenness is provided in the surface of thefirst semiconductor layer 11.

In the semiconductor light emitting element 110 b as shown in FIG. 5B,the first semiconductor layer 11 of the first light emitting unit 10 uincludes a high impurity concentration layer 11 p and a low impurityconcentration layer 11 q having the first conductivity type. The highimpurity concentration layer 11 p is provided between the low impurityconcentration layer 11 q and the first light emitting layer 10L. Theimpurity concentration of the low impurity concentration layer 11 q islower than the impurity concentration of the high impurity concentrationlayer 11 p. The high impurity concentration layer 11 p is, for example,an n-type GaN layer. The low impurity concentration layer 11 q is, forexample, an undoped GaN layer. An AlGaN or AlN layer may be used as thelow impurity concentration layer 11 q. Even in the case where the lowimpurity concentration layer 11 q is an undoped semiconductor layer, thelow impurity concentration layer 11 q is included in the firstsemiconductor layer 11 for convenience.

In the semiconductor light emitting element 110 b, the surface 11 u isthe surface of the low impurity concentration layer 11 q. In such a caseas well, the unevenness 11 pd is provided in the surface (the surface 11u) of the low impurity concentration layer 11 q.

The light extraction efficiency can be increased by providing theunevenness 11 pd in the surface (the surface 11 u) on the lightextraction side.

The first light-transmissive conductive unit 42 a may include, forexample, a light-transmissive electrode. The transmittance of thelight-transmissive electrode for the emitted light is, for example, notless than 50%. The light-transmissive electrode is conductive. Thelight-transmissive electrode is formable having, for example, an ohmiccontact with the n-type semiconductor layer. The light-transmissiveelectrode is formable having, for example, an ohmic contact with thep-type semiconductor layer. For example, at least one selected from ITO,ITON, and ZnO is used as the light-transmissive electrode. The thicknessof the light-transmissive electrode is, for example, not less than 10 nmand not more than 10000 nm. A high transmittance is obtained when thethickness is thin. The current spreading properties improve when thethickness is thick because the sheet resistance decreases. For example,a thin metal may be used as the light-transmissive electrode. Oxidesother than those recited above may be used as the light-transmissiveelectrode.

In the case where the thickness of the first inter-light emitting unitdielectric layer 71 (e.g., a SiO₂ film) for bonding is thin, the heatdissipation from the light emitting unit of the upper layer is good.

Uneven structures for light extraction may be formed in the surfaces ofthe n-type semiconductor layers (e.g., the first semiconductor layer 11and the third semiconductor layer 23) in a state in which the n-typesemiconductor layers are exposed.

The first electrode 61 may not be provided in the region overlapping thefirst pad 41 p when projected onto the X-Y plane. The first electrode 61may not be provided in the region overlapping the second pad 42 p whenprojected onto the X-Y plane. The light that is emitted directly underthe pad is easily absorbed by the pad. The light extraction efficiencycan be increased by reducing the proportion that is absorbed.

The first electrode 61 may be provided only in the region overlappingthe first light-transmissive conductive unit 42 a when projected ontothe X-Y plane. Thereby, the light emitting region of the first lightemitting layer 10L and the light emitting region of the second lightemitting layer 20L substantially match. Thereby, uneven color (colorbreakup) can be reduced. For example, the first electrode 61 may not beprovided in the region overlapping the first interconnect unit 42 b whenprojected onto the X-Y plane.

The first electrode 61 may not have an ohmic contact with the fourthsemiconductor layer 24 in the region overlapping the first pad 41 p andin the region overlapping the second pad 42 p when projected onto theX-Y plane. The light that is emitted directly under the pad is easilyabsorbed by the pad. The light extraction efficiency can be increased byreducing the proportion that is absorbed.

The first electrode 61 may have an ohmic contact with the fourthsemiconductor layer 24 only in the region overlapping the firstlight-transmissive conductive unit 42 a when projected onto the X-Yplane. In other words, the first electrode 61 may not have an ohmiccontact with the fourth semiconductor layer 24 in the region notoverlapping the first light-transmissive conductive unit 42 a whenprojected onto the X-Y plane. Thereby, the light emitting region of thefirst light emitting layer 10L and the light emitting region of thesecond light emitting layer 20L substantially match. Thereby, unevencolor (color breakup) can be reduced.

In the case where the second pad 42 p is formed on the firstlight-transmissive conductive unit 42 a, the first light-transmissiveconductive unit 42 a (the ITO) can be used as an etching stop layer whenperforming dry etching of the crystal layer of the second light emittingunit 20 u. If a metal layer is used as the etching stop layer, there arecases where by-products of the reaction with the dry etching gas or themetal removed by the etching adhere around the metal layer. Therefore,the structure may become nonuniform or leaks may occur. Also, the yieldmay decrease. Further, the life may shorten.

By using the ITO film of the first light-transmissive conductive unit 42a as the etching stop layer, the structure becomes uniform; and leaksare suppressed easily. The yield is increased easily; and the life canbe longer.

In the case where the second pad 42 p is formed on the firstlight-transmissive conductive unit 42 a (the ITO), it is unnecessary topattern the ITO film prior to the bonding. Therefore, the patterning iseasy.

On the other hand, in the case where the second pad 42 p is formed onthe first interconnect unit 42 b, the contact resistance between thesecond pad 42 p and the first interconnect unit 42 b can be low. Then,the adhesion between the second pad 42 p and the first interconnect unit42 b is high. There are cases where the contact resistance between theITO and the metal is relatively high and the adhesion is poor. Byforming the second pad 42 p on the first interconnect unit 42 b, lowcontact resistance and good adhesion are obtained easily.

For the second light emitting unit 20 u, for example, as recited above,Au—Sn solder is used to bond the first electrode 61 and the supportlayer 66 c. For example, the bonding may be liquid phase diffusionbonding using solder of Au—In, Ni—Sn, etc. The bonding temperature is,for example, not less than 200° C. and not more than 250° C. Conversely,the melting point of the solder for the liquid phase diffusion bondingusing the solder of Au—In, Ni—Sn, etc., can be high, i.e., not less than400° C. and not more than 1100° C. Thereby, the temperature of theprocesses implemented after the bonding process using the solder can belower than the temperature of the bonding process.

FIG. 6 is a schematic cross-sectional view illustrating anothersemiconductor light emitting element according to the first embodiment.

FIG. 6 is a cross-sectional view corresponding to a line A1-A2 crosssection of FIG. 1A.

In the semiconductor light emitting element 112 according to theembodiment as shown in FIG. 6, a first optical layer 71 d is provided inthe first inter-light emitting unit dielectric layer 71 provided betweenthe first light emitting unit 10 u and the second light emitting unit 20u.

In the example, the first inter-light emitting unit dielectric layer 71includes the first dielectric film 71 a, the second dielectric film 71b, and the first optical layer 71 d. The first dielectric film 71 a isdisposed between the first light emitting unit 10 u and the second lightemitting unit 20 u. The second dielectric film 71 b is disposed betweenthe second light emitting unit 20 u and the first dielectric film 71 a.In the example, the first optical layer 71 d is disposed between thefirst dielectric film 71 a and the second dielectric film 71 b.

The first optical layer 71 d transmits the light (the second light)emitted from the second light emitting layer 20L and reflects the light(the first light) emitted from the first light emitting layer 10L. Thefirst optical layer 71 d is, for example, a dichromic mirror.

The transmittance of the first optical layer 71 d for the second lightis higher than the transmittance of the first optical layer 71 d for thefirst light. The reflectance of the first optical layer 71 d to thefirst light is higher than the reflectance of the first optical layer 71d to the second light.

For example, the first optical layer 71 d may be provided between thefirst dielectric film 71 a and the first light emitting unit 10 u. Atleast a portion of the first optical layer 71 d may contact the firstlight emitting unit 10 u. For example, the first optical layer 71 d maybe provided between the second dielectric film 71 b and the second lightemitting unit 20 u. At least a portion of the first optical layer 71 dmay contact the second light emitting unit 20 u.

At least a portion of the first optical layer 71 d may be formed by, forexample, adjusting the thickness of the SiO₂ film (the second dielectricfilm 71 b) of the lower layer for bonding. At least a portion of thefirst optical layer 71 d may be formed by, for example, adjusting thethickness of the SiO₂ film (the first dielectric film 71 a) of the upperlayer for bonding.

The first optical layer 71 d may include the same material as the firstdielectric film 71 a or a different material. The first optical layer 71d may include the same material as the second dielectric film 71 b or adifferent material.

The first optical layer 71 d may include any material transmissive tothe second light. The first optical layer 71 d has bonding strength andis insulative.

In the embodiment, for example, the first interconnect unit 42 b and thefirst extension portion 41 v of the first conductive layer 41 are usedas the interconnect electrode. The width of the interconnect electrodemay not be 10 μm. The interconnect electrode includes a material havinggood adhesion with the other layers and low resistivity. In the casewhere the width of the interconnect electrode is narrow (small), thesurface area of the absorption region with respect to the emitted lightdecreases. Thereby, the light extraction efficiency increases. In thecase where the width of the interconnect electrode is wide, theinterconnect resistance decreases; and the current spreading increases.Thereby, the luminous efficiency increases; the operating voltagedecreases; and the life is longer.

The interconnect resistance of the interconnect electrode can be reducedby setting the thickness of the interconnect electrode to be thick. Inthe case where the thickness of the interconnect electrode isexcessively thick, the polishing amount (the thickness) that isnecessary in the planarizing in the CMP process becomes large.

A solder layer may be provided in a portion of the first connectionelectrode 51. For example, the solder layer may be provided on thesurface of the first metal unit 51 a in the state prior to bonding thefirst light emitting unit 10 u and the second light emitting unit 20 u.For example, the solder layer may be provided on the surface of thesecond metal unit 51 b in the state prior to the bonding. For example, amore reliable bond is obtained by bonding the first metal unit 51 a andthe second metal unit 51 b to each other with the solder layer.

FIG. 7A to FIG. 7D are schematic views illustrating anothersemiconductor light emitting element according to the first embodiment.

FIG. 7A is a plan view. FIG. 7B is a line A1-A2 cross-sectional view ofFIG. 1A. FIG. 7C is a line B1-B2 cross-sectional view of FIG. 7A. FIG.7D is a line C1-C2 cross-sectional view of FIG. 7A.

As shown in FIG. 7B to FIG. 7D, the semiconductor light emitting element113 according to the embodiment further includes a third light emittingunit 30 u, a third pad 43 p, and a second inter-light emitting unitdielectric layer 72 in addition to the first electrode 61, the firstlight emitting unit 10 u, the second light emitting unit 20 u, the firstconnection electrode 51, the first dielectric layer 51 i, the first pad41 p, the second pad 42 p, and the first inter-light emitting unitdielectric layer 71. In the example, the first conductive layer 41, thesecond conductive layer 42, and a third conductive layer 43 areprovided.

In the semiconductor light emitting element 113, configurations that aresimilar to those of the semiconductor light emitting element 110 areapplicable to the first electrode 61, the first light emitting unit 10u, the second light emitting unit 20 u, the first connection electrode51, the first dielectric layer 51 i, the first pad 41 p, the second pad42 p, the first inter-light emitting unit dielectric layer 71, the firstconductive layer 41, and the second conductive layer 42; and adescription is omitted. The third light emitting unit 30 u, the thirdpad 43 p, the second inter-light emitting unit dielectric layer 72, andthe third conductive layer 43 will now be described.

The first light emitting unit 10 u is disposed between the third lightemitting unit 30 u and the second light emitting unit 20 u. The thirdlight emitting unit 30 u includes a fifth semiconductor layer 35, asixth semiconductor layer 36, and a third light emitting layer 30L.

The fifth semiconductor layer 35 is separated from the first lightemitting unit 10 u in the first direction D1. The fifth semiconductorlayer 35 has a fifth conductivity type. The first light emitting unit 10u is disposed between the fifth semiconductor layer 35 and the secondlight emitting unit 20 u. The fifth semiconductor layer 35 includes athird semiconductor portion 35 a and a fourth semiconductor portion 35b. The fourth semiconductor portion 35 b is arranged with the thirdsemiconductor portion 35 a in a direction crossing the first directionD1.

The sixth semiconductor layer 36 is provided between the fourthsemiconductor portion 35 b and the first light emitting unit 10 u. Thesixth semiconductor layer 36 has a sixth conductivity type. The sixthconductivity type is different from the fifth conductivity type.

The third light emitting layer 30L is provided between the fourthsemiconductor portion 35 b and the sixth semiconductor layer 36. Thethird light emitting layer 30L emits a third light. The third light hasa third peak wavelength. The third peak wavelength is different from thefirst peak wavelength and different from the second peak wavelength.

For example, the fifth conductivity type is the same as the thirdconductivity type. For example, the sixth conductivity type is the sameas the second conductivity type. For example, the first conductivitytype, the third conductivity type, and the fifth conductivity type arethe n-type; and the second conductivity type, the fourth conductivitytype, and the sixth conductivity type are the p-type. In the embodiment,the first conductivity type, the third conductivity type, and the fifthconductivity type may be the p-type; and the second conductivity type,the fourth conductivity type, and the sixth conductivity type may be then-type. In the embodiment, the first to sixth conductivity types arearbitrary. Hereinbelow, the case where the first conductivity type, thethird conductivity type, and the fifth conductivity type are the n-typeand the second conductivity type, the fourth conductivity type, and thesixth conductivity type are the p-type will be described.

A second connection electrode 52 is electrically connected with thethird semiconductor portion 35 a. The second connection electrode 52extends in the first direction D1 and is electrically connected with thefirst semiconductor layer 11.

A second dielectric layer 52 i is provided between the second connectionelectrode 52 and the sixth semiconductor layer 36 and between the secondconnection electrode 52 and the third light emitting layer 30L.

The third pad 43 p is electrically connected with the sixthsemiconductor layer 36.

The second inter-light emitting unit dielectric layer 72 is providedbetween the third light emitting unit 30 u and the first light emittingunit 10 u. The second inter-light emitting unit dielectric layer 72 islight-transmissive.

In the example, the third conductive layer 43 is provided; and thesecond connection electrode 52 is electrically connected with the thirdpad 43 p via the third conductive layer 43.

The third conductive layer 43 is electrically connected with the sixthsemiconductor layer 36. The third conductive layer 43 includes a thirdinter-layer portion 43 t and a third pad disposition portion 43 u. Thethird inter-layer portion 43 t is provided between the third lightemitting unit 30 u and the first light emitting unit 10 u. The third paddisposition portion 43 u is arranged with the third inter-layer portion43 t in a direction crossing the first direction D1.

The third pad 43 p is electrically connected with the third paddisposition portion 43 u. The second dielectric layer 52 i is furtherdisposed between the second connection electrode 52 and the thirdconductive layer 43. In the example, the third conductive layer 43 isdisposed between the third pad 43 p and the first light emitting unit 10u.

In the example, the third conductive layer 43 includes a secondlight-transmissive conductive unit 43 a and a second interconnect unit43 b. The second light-transmissive conductive unit 43 a is providedbetween the third light emitting unit 30 u and the second inter-lightemitting unit dielectric layer 72. The second light-transmissiveconductive unit 43 a is electrically connected with the sixthsemiconductor layer 36.

The second light-transmissive conductive unit 43 a includes, forexample, an oxide including at least one element selected from the groupconsisting of In, Sn, Zn, and Ti. The second light-transmissiveconductive unit 43 a includes, for example, ITO, etc. The secondlight-transmissive conductive unit 43 a may include a thin film of ametal.

The second interconnect unit 43 b is provided between the secondlight-transmissive conductive unit 43 a and the second inter-lightemitting unit dielectric layer 72. The second interconnect unit 43 b iselectrically connected with the second light-transmissive conductiveunit 43 a. The optical transmittance of the second interconnect unit 43b is lower than the optical transmittance of the secondlight-transmissive conductive unit 43 a. The second interconnect unit 43b includes, for example, at least one selected from Au, Al, Ti, and Pt.

In the example, at least a portion of the second light-transmissiveconductive unit 43 a is disposed between the third pad 43 p and thefirst light emitting unit 10 u. In other words, the secondlight-transmissive conductive unit 43 a is provided on the first lightemitting unit 10 u; and the third pad 43 p is provided on the secondlight-transmissive conductive unit 43 a.

The first pad 41 p also functions as the n-side pad of the third lightemitting unit 30 u. For example, the first pad 41 p is electricallyconnected with the first semiconductor layer 11 of the first lightemitting unit 10 u via the first conductive layer 41 and the firstconnection electrode 51. The first semiconductor layer 11 iselectrically connected with the fifth semiconductor layer 35 of thethird light emitting unit 30 u via the second connection electrode 52.

On the other hand, the third pad 43 p functions as the p-side pad of thethird light emitting unit 30 u. In other words, the third pad 43 p isconnected with the sixth semiconductor layer 36 via the third conductivelayer 43.

By applying a voltage first pad 41 p and the third pad 43 p, a currentis supplied to the third light emitting layer 30L; and light (the thirdlight) is emitted from the third light emitting layer 30L.

It is favorable for the third peak wavelength of the third light to belonger than the first peak wavelength of the first light. Also, it isfavorable for the first peak wavelength of the first light to be longerthan the second peak wavelength of the second light. Thereby, theabsorption is suppressed; and the light extraction efficiency increases.

For example, the second light that is emitted from the second lightemitting layer 20L is blue light; the first light that is emitted fromthe first light emitting layer 10L is green light; and the third lightthat is emitted from the third light emitting layer 30L is red light.However, in the embodiment, the colors (the peak wavelengths) of thelight emitted from the light emitting units are arbitrary.

In the example, the second connection electrode 52 includes a fourthmetal unit 52 d and a fifth metal unit 52 e. The fourth metal unit 52 dis disposed between the third semiconductor portion 35 a and at least aportion of the fifth metal unit 52 e. The fourth metal unit 52 d maycontact, for example, the third semiconductor portion 35 a. In theexample, the second connection electrode 52 further includes a sixthmetal unit 52 f. The sixth metal unit 52 f is provided between thefourth metal unit 52 d and the third semiconductor portion 35 a. Thesixth metal unit 52 f is, for example, the n-side electrode of the thirdlight emitting unit 30 u. The fifth metal unit 52 e is, for example, then-side electrode of the first light emitting unit 10 u.

The sixth metal unit 52 f includes a material having ohmic propertieswith the fifth semiconductor layer 35 and a low contact resistance. Thefifth metal unit 52 e includes, for example, a material having ohmicproperties with the first semiconductor layer 11 and a low contactresistance. In the example, the conductive layer 11 el described inregard to FIG. 1A and FIG. 1B may be further provided (the conductivelayer 11 el is not shown in FIG. 7C, etc.). In such a case, the fifthmetal unit 52 e may be connected with, for example, the conductive layer11 el with good adhesion. For example, a metal film including at leastone selected from the group consisting of Al, Ti, Cu, Ag, and Ta may beused as the sixth metal unit 52 f and the fifth metal unit 52 e. Analloy including the at least one selected from the group may be used. Astacked film including multiple metal films of the at least one selectedfrom the group may be used.

The fourth metal unit 52 d can electrically connect the fifth metal unit52 e and the sixth metal unit 52 f. For example, the fourth metal unit52 d may include a metal film including at least one selected from thegroup consisting of Al, Ti, Cu, Ag, Au, W, and Ni. An alloy includingthe at least one selected from the group may be used. A stacked filmincluding multiple metal films of the at least one selected from thegroup may be used.

As shown in FIG. 7A, the first pad 41 p does not overlap the second pad42 p when projected onto the X-Y plane. The third pad 43 p overlapsneither the first pad 41 p nor the second pad 42 p when projected ontothe X-Y plane.

FIG. 8A to FIG. 8F are schematic views illustrating anothersemiconductor light emitting element according to the first embodiment.

FIG. 8A is a cross-sectional view of the same cross section as FIG. 8C.FIG. 8B to FIG. 8F are schematic see-through plan views corresponding tothe regions R1 to R5 shown in FIG. 8A. The regions R1 to R5 are regionsparallel to the X-Y plane. The region R1 is the region including thefirst pad 41 p and the first conductive layer 41. The region R2 is theregion including the first light-transmissive conductive unit 42 a andthe first interconnect unit 42 b. The region R3 is the region includingthe second pad 42 p and the first light-transmissive conductive unit 42a. The region R4 is the region including the second light-transmissiveconductive unit 43 a and the second interconnect unit 43 b. The regionR5 is the region including the third pad 43 p and the secondlight-transmissive conductive unit 43 a.

As shown in FIG. 8B, the semiconductor light emitting element 110 has asubstantially rectangular planar configuration. In the region R1 in theexample, the first conductive layer 41 is provided along the sides ofthe rectangle. The first connection electrode 51 and the first pad 41 pare connected by the first conductive layer 41. The portion around thefirst connection electrode 51 is used as the first dielectric layer 51i. The remaining portion is used as the first inter-light emitting unitdielectric layer 71.

As shown in FIG. 8C, the first light-transmissive conductive unit 42 aand the first interconnect unit 42 b are provided in the region R2. Thefirst light-transmissive conductive unit 42 a and the first interconnectunit 42 b are electrically connected with each other. The firstdielectric layer 51 i is provided between the first connection electrode51 and the first light-transmissive conductive unit 42 a and between thefirst connection electrode 51 and the first interconnect unit 42 b.

As shown in FIG. 8B and FIG. 8C, in such a case as well, at least aportion of the first conductive layer 41 and at least a portion of thefirst interconnect unit 42 b overlap each other when projected onto theX-Y plane. For example, when projected onto the X-Y plane, at least aportion of the first extension portion 41 v of the first conductivelayer 41 and at least a portion of the first interconnect unit 42 boverlap each other.

As shown in FIG. 8D, the first light-transmissive conductive unit 42 aand the second pad 42 p are provided in the region R3. The firstlight-transmissive conductive unit 42 a and the second pad 42 p areelectrically connected with each other. The first dielectric layer 51 iis provided between the first connection electrode 51 and the firstlight-transmissive conductive unit 42 a. These conductive units areinsulated from each other.

As shown in FIG. 8E, the second light-transmissive conductive unit 43 aand the second interconnect unit 43 b are provided in the region R4. Thesecond light-transmissive conductive unit 43 a and the secondinterconnect unit 43 b are electrically connected with each other. Thesecond dielectric layer 52 i is provided between the second connectionelectrode 52 and the second light-transmissive conductive unit 43 a andbetween the second connection electrode 52 and the second interconnectunit 43 b.

As shown in FIG. 8B and FIG. 8E, at least a portion of the firstconductive layer 41 and at least a portion of the second interconnectunit 43 b overlap each other when projected onto the X-Y plane. Forexample, when projected onto the X-Y plane, at least a portion of thefirst extension portion 41 v of the first conductive layer 41 and atleast a portion of the second interconnect unit 43 b overlap each other.

As shown in FIG. 8F, the second light-transmissive conductive unit 43 aand the third pad 43 p are provided in the region R5. The secondlight-transmissive conductive unit 43 a and the third pad 43 p areelectrically connected with each other. The second dielectric layer 52 iis provided between the second connection electrode 52 and the secondlight-transmissive conductive unit 43 a. These conductive units areinsulated from each other.

According to the semiconductor light emitting element 113, a stackedsemiconductor light emitting element having a high efficiency can beprovided. In the semiconductor light emitting element 113, variousmodifications of the pattern arrangements of the components arepossible.

For example, an example of the method for manufacturing thesemiconductor light emitting element 113 will now be described.

The processes described in regard to the semiconductor light emittingelement 110 are applicable to the processes of the semiconductor lightemitting element 113 up to the bonding of the first light emitting unit10 u and the second light emitting unit 20 u. Examples of the formationof the third light emitting unit 30 u and the bonding of the third lightemitting unit 30 u and the first light emitting unit 10 u will now bedescribed.

A stacked body (a semiconductor wafer) that includes the third lightemitting unit 30 u is formed by processes similar to those of the firstlight emitting unit 10 u. A connection electrode is formed by making ahole from the surface (the sixth semiconductor layer 36) of the stackedbody to reach the fifth semiconductor layer 35 and by filling aconductive material into the hole. For example, the hole overlaps thefirst connection electrode 51 when projected onto the X-Y plane. A Culayer is formed by lift-off; and the hole is filled with the Cu layer.The thickness of the Cu layer is, for example, about 200 nm (e.g., notless than 100 nm and not more than 800 nm). Thereby, a portion (thefourth metal unit 52 d) of the second connection electrode 52 is formed.In the description recited above, the sixth metal unit 52 f may beformed prior to the formation of the fourth metal unit 52 d.

A light-transmissive insulating layer (e.g., a SiO₂ film) that is usedto form a portion of the second inter-light emitting unit dielectriclayer 72 is formed to cover the sixth metal unit 52 f.

The connection electrode (the fourth metal unit 52 d) may be formedafter the formation of the light-transmissive insulating layer (e.g.,the SiO₂ film). The method for forming the connection electrode (thefourth metal unit 52 d) includes, for example, lift-off combined withvapor deposition, sputtering, CVD, plating, or a combination of thesemethods.

The light-transmissive insulating layer (e.g., the SiO₂ film) recitedabove is planarized by CMP processing. At this time, the connectionelectrode (the fourth metal unit 52 d) recited above is exposed.

On the other hand, for example, a light-transmissive insulating layer(e.g., a SiO₂ film) is formed on the surface of the first light emittingunit 10 u (the surface of the first semiconductor layer 11). Thelight-transmissive insulating layer that is formed on the surface of thefirst light emitting unit 10 u and the light-transmissive insulatinglayer recited above that is formed on the surface of the third lightemitting unit 30 u are caused to oppose each other and are bonded.

Similarly to the description of the semiconductor light emitting element110, dry etching or wet etching of the crystal layers and thelight-transmissive insulating layers is performed; and the pads recitedabove are formed. Thereby, the semiconductor light emitting element 113is formed.

Three light emitting layers are provided in the semiconductor lightemitting element 113. Similar to the description recited above, four ormore light emitting layers may be stacked by implementing the processes.

In the semiconductor light emitting element 113, for example, the lightemission wavelengths of the light emitting layers are, for example, red,green, and blue. Thereby, for example, a white LED can be realizedwithout using a fluorescer. Stokes shift loss occurs due to thewavelength conversion of fluorescers. Therefore, in the case where afluorescer is used, it is difficult to sufficiently increase theluminous efficiency. In the embodiment, a high luminous efficiency isobtained because it is unnecessary to use a fluorescer. A fluorescer maybe used in the embodiment.

FIG. 9 is a schematic cross-sectional view illustrating anothersemiconductor light emitting element according to the first embodiment.

FIG. 9 is a schematic view of a cross section corresponding to the lineB1-B2 cross section of FIG. 7A.

Similarly to the conductive layer 11 el described in regard to FIG. 1Ato FIG. 1B, in the semiconductor light emitting element 113 a accordingto the embodiment as shown in FIG. 9, a conductive layer 35 el isfurther provided on the fifth semiconductor layer 35. Otherwise, thesemiconductor light emitting element 113 a according to the embodimentis similar to the semiconductor light emitting element 113.

In the semiconductor light emitting element 113 a, the fifthsemiconductor layer 35 is disposed between the conductive layer 35 eland the third light emitting layer 30L. The conductive layer 35 el isused as, for example, the n-side electrode of the third light emittingunit 30 u. By providing the conductive layer 35 el, the currentspreading of the fifth semiconductor layer 35 of the third lightemitting unit 30 u increases. Thereby, the operating voltage decreases;and the luminous efficiency increases. At least a portion of theconductive layer 35 el may overlap at least a portion of at least oneselected from the conductive layer 11 el, the first conductive layer 41,and the first interconnect unit 42 b when projected onto the X-Y plane.Thereby, color breakup is suppressed; and the absorption of the emittedlight by the conductive layer 35 el is suppressed. Thereby, the unevencolor can be reduced; and the light extraction efficiency can beincreased. The conductive layer 35 el may be light-transmissive. Theconductive layer 35 el may be provided as necessary and may be omitted.

FIG. 10A and FIG. 10B are schematic cross-sectional views illustratingother semiconductor light emitting elements according to the firstembodiment.

These drawings illustrate a portion of the third light emitting unit 30u.

In the semiconductor light emitting element 113 b as shown in FIG. 10A,the third light emitting unit 30 u has a surface 35 u on the sideopposite to the first light emitting unit 10 u. The surface 35 u is asurface on the light extraction side of the semiconductor light emittingelement. In the semiconductor light emitting element 113 a, anunevenness 35 pd is provided in the surface 35 u. In the example, theunevenness is provided in the surface of the fifth semiconductor layer35.

In the semiconductor light emitting element 113 c as shown in FIG. 10B,the fifth semiconductor layer 35 of the third light emitting unit 30 uincludes a high impurity concentration layer 35P and a low impurityconcentration layer 35 q having the fifth conductivity type. The highimpurity concentration layer 35P is provided between the low impurityconcentration layer 35 q and the third light emitting layer 30L. Theimpurity concentration of the low impurity concentration layer 35 q islower than the impurity concentration of the high impurity concentrationlayer 35P. The high impurity concentration layer 35P is, for example, ann-type GaN layer. The low impurity concentration layer 35 q is, forexample, an undoped GaN layer. An AlGaN or AlN layer may be used as thelow impurity concentration layer 35 q. Even in the case where the lowimpurity concentration layer 35 q is an undoped semiconductor layer, thelow impurity concentration layer 35 q also is included in the fifthsemiconductor layer 35 for convenience.

In the semiconductor light emitting element 113 b, the surface 35 u isthe surface of the low impurity concentration layer 35 q. In such a caseas well, the unevenness 35 pd is provided in the surface (the surface 35u) of the low impurity concentration layer 35 q.

In the semiconductor light emitting elements 113 a and 113 b, the lightis emitted to the outside by passing through the third light emittingunit 30 u. In the semiconductor light emitting elements 113 a and 113 b,the surface 35 u is the surface on the light extraction side. The lightextraction efficiency can be increased by providing the unevenness 35 pdin the surface 35 u.

FIG. 11 is a schematic cross-sectional view illustrating anothersemiconductor light emitting element according to the first embodiment.FIG. 11 is a cross-sectional view corresponding to the line A1-A2 crosssection of FIG. 7A.

In the semiconductor light emitting element 114 according to theembodiment as shown in FIG. 11, a second optical layer 72 d is providedin the second inter-light emitting unit dielectric layer 72 providedbetween the third light emitting unit 30 u and the first light emittingunit 10 u.

In the example, the second inter-light emitting unit dielectric layer 72includes a third dielectric film 72 a, a fourth dielectric film 72 b,and the second optical layer 72 d. The third dielectric film 72 a isdisposed between the first light emitting unit 10 u and the second lightemitting unit 20 u. The fourth dielectric film 72 b is disposed betweenthe second light emitting unit 20 u and the third dielectric film 72 a.In the example, the second optical layer 72 d is disposed between thethird dielectric film 72 a and the fourth dielectric film 72 b.

The second optical layer 72 d transmits the light (the first light)emitted from the first light emitting layer 10L and reflects the light(the third light) emitted from the third light emitting layer 30L. Thesecond optical layer 72 d is, for example, a dichromic mirror.

The transmittance of the second optical layer 72 d for the first lightis higher than the transmittance of the second optical layer 72 d forthe third light. The reflectance of the second optical layer 72 d to thethird light is higher than the reflectance of the second optical layer72 d to the first light.

The transmittance of the second optical layer 72 d for the second lightis higher than the transmittance of the second optical layer 72 d forthe third light. The reflectance of the second optical layer 72 d to thethird light is higher than the reflectance of the second optical layer72 d to the second light.

For example, the second optical layer 72 d may be provided between thethird dielectric film 72 a and the first light emitting unit 10 u. Forexample, the second optical layer 72 d may be provided between thefourth dielectric film 72 b and the second light emitting unit 20 u.

At least a portion of the second optical layer 72 d may be formed by,for example, adjusting the thickness of the SiO₂ film (the fourthdielectric film 72 b) of the lower layer for bonding. At least a portionof the second optical layer 72 d may be formed by, for example,adjusting the thickness of the SiO₂ film (the third dielectric film 72a) of the upper layer for bonding.

The second optical layer 72 d may include the same material as the thirddielectric film 72 a or a different material. The second optical layer72 d may include the same material as the fourth dielectric film 72 b ora different material.

The second optical layer 72 d may include any material that istransmissive to the first light and the second light. The second opticallayer 72 d has bonding strength and is insulative.

Second Embodiment

FIG. 12 is a schematic cross-sectional view illustrating a semiconductorlight emitting element according to a second embodiment.

As shown in FIG. 12, the semiconductor light emitting element 120according to the embodiment includes a pad unit PD0, the first lightemitting unit 10 u, the second light emitting unit 20 u, the firstelectrode 61, an insulating support layer 66 i, a first conductive layer91, the first inter-light emitting unit dielectric layer 71, a firstconnection electrode 81, a second connection electrode 82, a thirdconnection electrode 83, a fourth connection electrode 84, a firstdielectric layer 81 i, a second dielectric layer 82 i, and a thirddielectric layer 83 i.

The pad unit PD0 includes a first pad PD1, a second pad PD2, and a thirdpad PD3. The second pad PD2 is separated from the first pad PD1 in afirst surface pl 1. The third pad PD3 is separated from the first padPD1 and separated from the second pad PD2 in the first surface pl 1.

For example, the first surface pl 1 intersects the Z-axis direction. Onedirection perpendicular to the Z-axis direction is taken as an X-axisdirection. A direction perpendicular to the Z-axis direction and theX-axis direction is taken as a Y-axis direction. The Z-axis direction istaken to be parallel to the first direction D1.

The first light emitting unit 10 u includes the first semiconductorlayer 11, the second semiconductor layer 12, and the first lightemitting layer 10L.

The first semiconductor layer 11 is separated from the pad unit PD0 inthe first direction D1 (a direction intersecting the first surface pl1). In the example, the first direction D1 is perpendicular to the firstsurface pl 1. The first semiconductor layer 11 includes the firstsemiconductor portion 11 a and the second semiconductor portion 11 b.The second semiconductor portion 11 b is arranged with the firstsemiconductor portion 11 a in a direction crossing the first directionD1. The first semiconductor layer 11 has the first conductivity type.

The second semiconductor layer 12 is provided between the secondsemiconductor portion 11 b and the pad unit PD0. The secondsemiconductor layer 12 has the second conductivity type. The secondconductivity type is different from the first conductivity type.

The first light emitting layer 10L is provided between the secondsemiconductor portion 11 b and the second semiconductor layer 12. Thefirst light emitting layer 10L emits the first light. The first lighthas the first peak wavelength.

The second light emitting unit 20 u is provided between the first lightemitting unit 10 u and the pad unit PD0. The second light emitting unit20 u includes the third semiconductor layer 23, the fourth semiconductorlayer 24, and the second light emitting unit 20 u.

The third semiconductor layer 23 is provided between the pad unit PD0and the first light emitting unit 10 u. The third semiconductor layer 23includes a third semiconductor portion 23 a and a fourth semiconductorportion 23 b. The fourth semiconductor portion 23 b is arranged with thethird semiconductor portion 23 a in a direction intersecting the firstdirection D1. The third semiconductor layer 23 has the thirdconductivity type.

The fourth semiconductor layer 24 is provided between the fourthsemiconductor portion 23 b and the pad unit PD0. The fourthsemiconductor layer 24 has the fourth conductivity type. The fourthconductivity type is different from the third conductivity type.

The second light emitting layer 20L is provided between the fourthsemiconductor portion 23 b and the fourth semiconductor layer 24. Thesecond light emitting layer 20L emits the second light. The second lighthas the second peak wavelength.

The first electrode 61 is provided between the pad unit PD0 and thesecond light emitting unit 20 u and is reflective. The insulatingsupport layer 66 i is provided between the pad unit PD0 and the firstelectrode 61.

The first conductive layer 91 is provided between the first lightemitting unit 10 u and the second light emitting unit 20 u. The firstconductive layer 91 extends in a direction crossing the first directionD1. The first conductive layer 91 is electrically connected with thesecond semiconductor layer 12.

The first inter-light emitting unit dielectric layer 71 is providedbetween the first light emitting unit 10 u and the second light emittingunit 20 u and between the first conductive layer 91 and the second lightemitting unit 20 u and is light-transmissive.

The first connection electrode 81 is provided between the firstsemiconductor portion 11 a and the third semiconductor layer 23 andpierces the first inter-light emitting unit dielectric layer 71 in thefirst direction D1. The first connection electrode 81 electricallyconnects the first semiconductor portion 11 a and the thirdsemiconductor layer 23.

The first dielectric layer 81 i is provided between the first connectionelectrode 81 and the second semiconductor layer 12, between the firstconnection electrode 81 and the first light emitting layer 10L, andbetween the first connection electrode 81 and the first conductive layer91.

The second connection electrode 82 is provided between the thirdsemiconductor portion 23 a and the first pad PD1. The second connectionelectrode 82 pierces the insulating support layer 66 i in the firstdirection D1. The second connection electrode 82 electrically connectsthe third semiconductor portion 23 a and the first pad PD1.

The second dielectric layer 82 i is provided between the secondconnection electrode 82 and the fourth semiconductor layer 24, betweenthe second connection electrode 82 and the second light emitting layer20L, and between the second connection electrode 82 and the firstelectrode 61.

The third connection electrode 83 is provided between the firstconductive layer 91 and the second pad PD2. The third connectionelectrode 83 pierces the first inter-light emitting unit dielectriclayer 71, the second light emitting unit 20 u, and the insulatingsupport layer 66 i in the first direction D1. The third connectionelectrode 83 electrically connects the first conductive layer 91 and thesecond pad PD2.

The third dielectric layer 83 i is provided between the third connectionelectrode 83 and the second light emitting unit 20 u and between thethird connection electrode 83 and the first electrode 61.

The fourth connection electrode 84 is provided between the firstelectrode 61 and the third pad PD3. The fourth connection electrode 84pierces the insulating support layer 66 i in the first direction D1 andelectrically connects the first electrode 61 and the third pad PD3.

For example, the first conductivity type is the same as the thirdconductivity type. For example, the second conductivity type is the sameas the fourth conductivity type. For example, the first conductivitytype and the third conductivity type are the n-type; and the secondconductivity type and the fourth conductivity type are the p-type. Inthe embodiment, the first conductivity type and the third conductivitytype may be the p-type; and the second conductivity type and the fourthconductivity type may be the n-type. In the embodiment, the first tofourth conductivity types are arbitrary. Hereinbelow, the case isdescribed where the first conductivity type and the third conductivitytype are the n-type and the second conductivity type and the fourthconductivity type are the p-type.

In the semiconductor light emitting element 120, the first pad PD1 iselectrically connected with the third semiconductor layer 23 via thesecond connection electrode 82. The third semiconductor layer 23 iselectrically connected with the first semiconductor layer 11 via thefirst connection electrode 81. In other words, the first pad PD1 isconnected with both the third semiconductor layer 23 and the firstsemiconductor layer 11. The first pad PD1 functions as, for example, then-type electrode of the first light emitting unit 10 u and the secondlight emitting unit 20 u.

The second pad PD2 is electrically connected with the secondsemiconductor layer 12 via the third connection electrode 83 and thefirst conductive layer 91. The second pad PD2 functions as, for example,the p-side electrode of the first light emitting unit 10 u.

The third pad PD3 is electrically connected with the fourthsemiconductor layer 24 via the fourth connection electrode 84 and thefirst electrode 61. The third pad PD3 functions as, for example, thep-side electrode of the second light emitting unit 20 u.

By applying a voltage between the first pad PD1 and the third pad PD3, acurrent is supplied to the second light emitting layer 20L; and light(the second light) is emitted from the second light emitting layer 20L.By applying a voltage between the first pad PD1 and the second pad PD2,a current is supplied to the second light emitting layer 20L; and light(the first light) is emitted from the first light emitting layer 10L.

For example, the second peak wavelength is shorter than the first peakwavelength. For example, the second light is blue light; and the firstlight is at least one selected from yellow light and green light. Thecolor (the peak wavelength) of the light is arbitrary.

According to the embodiment, a stacked semiconductor light emittingelement having a high efficiency can be provided. In the embodiment, apad is not provided on the side of the light extraction surface.Thereby, the light extraction efficiency increases further.

Thus, in the embodiment, via electrodes (connection electrodes) are usedas the conduction paths to the crystal layers. The via electrodes may bemade similarly to the methods described in the first embodiment.

Further, in the embodiment, the third light emitting unit may beprovided. The first light emitting unit 10 u is disposed between thethird light emitting unit and the second light emitting unit 20 u. Insuch a case, for example, the second light that is emitted from thesecond light emitting layer 20L is blue light; the first light that isemitted from the first light emitting layer 10L is green light; and thethird light that is emitted from the third light emitting layer of thethird light emitting unit is red light.

In the example, the first connection electrode 81 includes a first metalunit 81 a and a second metal unit 81 b. The first metal unit 81 a isdisposed between the first semiconductor portion 11 a and at least aportion of the second metal unit 81 b. The first metal unit 81 a maycontact, for example, the first semiconductor portion 11 a. In theexample, the first connection electrode 81 further includes a thirdmetal unit 81 c. The third metal unit 81 c is provided between the firstmetal unit 81 a and the first semiconductor portion 11 a. The thirdmetal unit 81 c is, for example, the n-side electrode of the first lightemitting unit 10 u. The second metal unit 81 b is, for example, then-side electrode of the second light emitting unit 20 u.

The third metal unit 81 c includes a material having ohmic propertieswith the first semiconductor layer 11 and a low contact resistance. Thesecond metal unit 81 b may include, for example, a material having ohmicproperties with the third semiconductor layer 23 and a low contactresistance. The second metal unit 81 b may be bonded with good adhesionto, for example, a third semiconductor layer electrode 23 e describedbelow. For example, a metal film including at least one selected fromthe group consisting of Al, Ti, Cu, Ag, and Ta may be used as the firstmetal unit 81 a and the second metal unit 81 b. An alloy including theat least one selected from the group may be used. A stacked filmincluding multiple metal films of the at least one selected from thegroup may be used.

The first metal unit 81 a can electrically connect the second metal unit81 b and the third metal unit 81 c. For example, the first metal unit 81a may include a metal film including at least one selected from thegroup consisting of Al, Ti, Cu, Ag, Au, W, and Ni. An alloy includingthe at least one selected from the group may be used. A stacked filmincluding multiple metal films of the at least one selected from thegroup may be used.

In the example, the second connection electrode 82 includes a fourthmetal unit 82 a and a fifth metal unit 82 b. The fourth metal unit 82 ais disposed between the third semiconductor portion 23 a and at least aportion of the fifth metal unit 82 b. The fourth metal unit 82 a maycontact, for example, the third semiconductor portion 23 a. In theexample, the second connection electrode 82 further includes a sixthmetal unit 82 c. The sixth metal unit 82 c is provided between thefourth metal unit 82 a and the third semiconductor portion 23 a. Thesixth metal unit 82 c is, for example, the n-side electrode of thesecond light emitting unit 20 u.

In the example, the third connection electrode 83 includes a seventhmetal unit 83 a, an eighth metal unit 83 b, and a ninth metal unit 83 c.The eighth metal unit 83 b is disposed between the first conductivelayer 91 and at least a portion of the ninth metal unit 83 c. Theseventh metal unit 83 a is disposed between the first conductive layer91 and at least a portion of the eighth metal unit 83 b.

In the example, the fourth connection electrode 84 includes a tenthmetal unit 84 a and an eleventh metal unit 84 b. The tenth metal unit 84a is disposed between the first electrode 61 and at least a portion ofthe eleventh metal unit 84 b.

At least one selected from the first metal unit 81 a, the second metalunit 81 b, the fourth metal unit 82 a, the fifth metal unit 82 b, theseventh metal unit 83 a, the eighth metal unit 83 b, the ninth metalunit 83 c, the tenth metal unit 84 a, and the eleventh metal unit 84 bincludes, for example, at least one selected from Al, Ti, Cu, Ag, Au, W,and Ni. The third metal unit 81 c and the sixth metal unit 82 c include,for example, at least one selected from Al, Ti, Cu, Ag, and Ta.

In the example, the first conductive layer 91 includes a firstlight-transmissive conductive unit 91 a and a first interconnect unit 91b. The first light-transmissive conductive unit 91 a is provided betweenthe first light emitting unit 10 u and the first inter-light emittingunit dielectric layer 71. The first light-transmissive conductive unit91 a is electrically connected with the second semiconductor layer 12.

The first light-transmissive conductive unit 91 a includes, for example,an oxide including at least one element selected from the groupconsisting of In, Sn, Zn, and Ti. The first light-transmissiveconductive unit 91 a includes, for example, ITO, etc. The firstlight-transmissive conductive unit 91 a may include a thin film of ametal. The first light-transmissive conductive unit 91 a may be providedas necessary and may be omitted.

The first interconnect unit 91 b is provided, for example, between thefirst light-transmissive conductive unit 91 a and the first inter-lightemitting unit dielectric layer 71. The first interconnect unit 91 b iselectrically connected with the first light-transmissive conductive unit91 a. The optical transmittance of the first interconnect unit 91 b islower than the optical transmittance of the first light-transmissiveconductive unit 91 a. A metal having a low resistivity is suited to thefirst interconnect unit 91 b. The first interconnect unit 91 b includes,for example, at least one selected from the group consisting of Al, Au,Ag, and Cu, an alloy including the at least one selected from the group,or a stacked film including a film of the at least one selected from thegroup. The first interconnect unit 91 b may be provided as necessary andmay be omitted.

In the example, the third semiconductor layer electrode 23 e is providedbetween the third semiconductor layer 23 and the first inter-lightemitting unit dielectric layer 71. The third semiconductor layerelectrode 23 e is used to form an interconnect electrode for the thirdsemiconductor layer 23. For example, at least a portion of the thirdsemiconductor layer electrode 23 e and at least a portion of the firstconductive layer 91 overlap each other when projected onto the X-Yplane. Thereby, the surface area of the absorbing regions can bereduced; and the light extraction efficiency increases. The thirdsemiconductor layer electrode 23 e may be provided as necessary and maybe omitted.

In the example, a light-transmissive bonding layer 75 is providedbetween the first electrode 61 and the insulating support layer 66 i.The bonding layer 75 includes, for example, a SiO₂ film, etc. Thebonding layer 75 may be provided as necessary and may be omitted.

In the embodiment, the method for depositing the semiconductor layer mayinclude, for example, metal-organic chemical vapor deposition (MOCVD),metal-organic vapor phase epitaxy, etc.

According to the embodiments, a stacked semiconductor light emittingelement having a high efficiency can be provided.

In the specification, “nitride semiconductor” includes all compositionsof semiconductors of the chemical formula B_(x)In_(y)Al_(z)Ga_(1-x-y-z)N(0≦x≦1, 0≦y≦1, 0≦z≦1, and x+y+z≦1) for which the composition ratios x,y, and z are changed within the ranges respectively. “Nitridesemiconductor” further includes Group V elements other than N (nitrogen)in the chemical formula recited above, various elements added to controlvarious properties such as the conductivity type and the like, andvarious elements included unintentionally.

In the specification of the application, “perpendicular” and “parallel”refer to not only strictly perpendicular and strictly parallel but alsoinclude, for example, the fluctuation due to manufacturing processes,etc. It is sufficient to be substantially perpendicular andsubstantially parallel.

Hereinabove, embodiments of the invention are described with referenceto specific examples. However, the invention is not limited to thesespecific examples. For example, one skilled in the art may similarlypractice the invention by appropriately selecting specificconfigurations of components included in the semiconductor lightemitting element such as the electrode, the light emitting unit, thesemiconductor layer, the light emitting layer, the connection electrode,the dielectric layer, the dielectric film, the metal unit, the opticallayer, the support layer, the insulating support layer, etc., from knownart; and such practice is within the scope of the invention to theextent that similar effects can be obtained.

Further, any two or more components of the specific examples may becombined within the extent of technical feasibility and are included inthe scope of the invention to the extent that the purport of theinvention is included.

Moreover, all semiconductor light emitting devices practicable by anappropriate design modification by one skilled in the art based on thesemiconductor light emitting devices described above as embodiments ofthe invention also are within the scope of the invention to the extentthat the spirit of the invention is included.

Various other variations and modifications can be conceived by thoseskilled in the art within the spirit of the invention, and it isunderstood that such variations and modifications are also encompassedwithin the scope of the invention.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the inventions. Indeed, the novel embodiments described hereinmay be embodied in a variety of other forms; furthermore, variousomissions, substitutions and changes in the form of the embodimentsdescribed herein may be made without departing from the spirit of theinventions. The accompanying claims and their equivalents are intendedto cover such forms or modifications as would fall within the scope andspirit of the invention.

What is claimed is:
 1. A semiconductor light emitting element,comprising: a first electrode; a first light emitting unit including afirst semiconductor layer, a second semiconductor layer, and a firstlight emitting layer, the first semiconductor layer being separated fromthe first electrode in a first direction and including a firstsemiconductor portion and a second semiconductor portion, the secondsemiconductor portion being arranged with first semiconductor portion ina direction crossing the first direction, the second semiconductor layerbeing provided between the second semiconductor portion and the firstelectrode, the first light emitting layer being provided between thesecond semiconductor portion and the second semiconductor layer; asecond light emitting unit including a third semiconductor layer, afourth semiconductor layer, and a second light emitting layer, the thirdsemiconductor layer being provided between the first electrode and thefirst light emitting unit, the fourth semiconductor layer being providedbetween the third semiconductor layer and the first electrode, thefourth semiconductor layer being electrically connected with the firstelectrode, the second light emitting layer being provided between thethird semiconductor layer and the fourth semiconductor layer; a firstconductive layer including a first pad disposition portion and a firstinter-layer portion, the first inter-layer portion being providedbetween the first light emitting unit and the second light emittingunit, the first pad disposition portion being arranged with the firstinter-layer portion in a direction crossing the first direction, thefirst conductive layer being electrically connected with the thirdsemiconductor layer; a second conductive layer including a second paddisposition portion and a second inter-layer portion, the secondinter-layer portion being provided between the first light emitting unitand the second light emitting unit, the second pad disposition portionbeing arranged with the second inter-layer portion in a directioncrossing the first direction, the second conductive layer beingelectrically connected with the second semiconductor layer; a firstconnection electrode extending in the first direction and electricallyconnecting the first inter-layer portion and the first semiconductorportion; a first dielectric layer provided between the first connectionelectrode and the second semiconductor layer, between the firstconnection electrode and the first light emitting layer, and between thefirst connection electrode and the second conductive layer; a first padelectrically connected with the first pad disposition portion; a secondpad electrically connected with the second pad disposition portion; anda first inter-light emitting unit dielectric layer provided between thefirst light emitting unit and the second light emitting unit, betweenthe first light emitting unit and the first conductive layer, betweenthe second conductive layer and the second light emitting unit, andbetween the first conductive layer and the second conductive layer, thefirst inter-light emitting unit dielectric layer beinglight-transmissive.
 2. The element according to claim 1, wherein thefirst conductive layer is disposed between the first pad and the secondlight emitting unit, and the second conductive layer is disposed betweenthe second pad and the second light emitting unit.
 3. The elementaccording to claim 1, wherein the second conductive layer includes afirst light-transmissive conductive unit provided between the firstlight emitting unit and the first inter-light emitting unit dielectriclayer, the first light-transmissive conductive unit being electricallyconnected with the second semiconductor layer, and a first interconnectunit provided between the first light-transmissive conductive unit andthe first inter-light emitting unit dielectric layer, the firstinterconnect unit being electrically connected with the firstlight-transmissive conductive unit, an optical transmittance of thefirst interconnect unit being lower than an optical transmittance of thefirst light-transmissive conductive unit.
 4. The element according toclaim 3, wherein at least a portion of the first conductive layer and atleast a portion of the first interconnect unit overlap each other whenprojected onto a plane perpendicular to the first direction.
 5. Theelement according to claim 3, wherein the first conductive layer furtherincludes a first extension portion extending between the firstinter-layer portion and the first pad disposition portion, and at leasta portion of the first extension portion and at least a portion of thefirst interconnect unit overlap each other when projected onto a planeperpendicular to the first direction.
 6. The element according to claim3, wherein at least a portion of the first light-transmissive conductiveunit is disposed between the second pad and the second light emittingunit.
 7. The element according to claim 3, wherein at least a portion ofthe first interconnect unit is disposed between the second pad and thesecond light emitting unit.
 8. The element according to claim 1, whereinthe first pad does not overlap the second pad when projected onto aplane perpendicular to the first direction.
 9. The element according toclaim 1, further comprising: a support layer; and a second electrode,the second electrode being electrically connected with the firstelectrode, the first electrode being disposed between the second lightemitting unit and the second electrode, and the support layer beingdisposed between the first electrode and the second electrode.
 10. Theelement according to claim 9, further comprising a support layer-sidedielectric layer provided along an outer edge of the second lightemitting unit between the support layer and the second light emittingunit.
 11. The element according to claim 1, wherein the firstsemiconductor layer is of an n-type, the third semiconductor layer is ofthe n-type, the second semiconductor layer is of a p-type, and thefourth semiconductor layer is of the p-type.
 12. The element accordingto claim 1, wherein the first inter-light emitting unit dielectric layerincludes a first optical layer, the first light emitting layer isconfigured to emit a first light having a first peak wavelength, thesecond light emitting layer is configured to emit a second light havinga second peak wavelength different from the first peak wavelength, atransmittance of the first optical layer for the second light is higherthan a transmittance of the first optical layer for the first light, anda reflectance of the first optical layer to the first light is higherthan a reflectance of the first optical layer to the second light. 13.The element according to claim 1, further comprising: a third lightemitting unit including a fifth semiconductor layer, a sixthsemiconductor layer, and a third light emitting layer, the fifthsemiconductor layer being separated from the first light emitting unitin the first direction, the first light emitting unit being disposedbetween the fifth semiconductor layer and the second light emittingunit, the fifth semiconductor layer including a third semiconductorportion and a fourth semiconductor portion, the fourth semiconductorportion being arranged with the third semiconductor portion in adirection crossing the first direction, the sixth semiconductor layerbeing provided between the fourth semiconductor portion and the firstlight emitting unit, the third light emitting layer being providedbetween the fourth semiconductor portion and the sixth semiconductorlayer; a second connection electrode extending in the first directionand electrically connecting the third semiconductor portion and thefirst semiconductor layer; a second dielectric layer provided betweenthe second connection electrode and the sixth semiconductor layer andbetween the second connection electrode and the third light emittinglayer; a third pad electrically connected with the sixth semiconductorlayer; and a second inter-light emitting unit dielectric layer providedbetween the third light emitting unit and the first light emitting unit,the second inter-light emitting unit dielectric layer beinglight-transmissive.
 14. The element according to claim 13, furthercomprising a third conductive layer electrically connected with thesixth semiconductor layer, the third conductive layer including a thirdinter-layer portion and a third pad disposition portion, the thirdinter-layer portion being provided between the third light emitting unitand the first light emitting unit, the third pad disposition portionbeing arranged with the third inter-layer portion in a directioncrossing the first direction, the third pad being electrically connectedwith the third pad disposition portion, and the second dielectric layerbeing further disposed between the second connection electrode and thethird conductive layer.
 15. The element according to claim 14, whereinthe third conductive layer is disposed between the third pad and thefirst light emitting unit.
 16. The element according to claim 14,wherein the third conductive layer includes a second light-transmissiveconductive unit provided between the third light emitting unit and thesecond inter-light emitting unit dielectric layer, the secondlight-transmissive conductive unit being electrically connected with thesixth semiconductor layer, and a second interconnect unit providedbetween the second light-transmissive conductive unit and the secondinter-light emitting unit dielectric layer, the second interconnect unitbeing electrically connected with the second light-transmissiveconductive unit, an optical transmittance of the second interconnectunit being lower than an optical transmittance of the secondlight-transmissive conductive unit.
 17. The element according to claim16, wherein at least a portion of the second light-transmissiveconductive unit is disposed between the third pad and the first lightemitting unit.
 18. The element according to claim 13, wherein the thirdlight emitting unit has a surface on a side opposite to the first lightemitting unit, and the surface on the side opposite to the first lightemitting unit is a surface on a light extraction side.
 19. Asemiconductor light emitting element, comprising: a pad unit including afirst pad, a second pad, and a third pad, the second pad being separatedfrom the first pad in a first surface, the third pad being separatedfrom the first pad and separated from the second pad in the firstsurface; a first light emitting unit including a first semiconductorlayer, a second semiconductor layer, and a first light emitting layer,the first semiconductor layer being separated from the pad unit in afirst direction and including a first semiconductor portion and a secondsemiconductor portion, the second semiconductor portion being arrangedwith the first semiconductor portion in a direction crossing the firstdirection, the first direction intersecting the first surface, thesecond semiconductor layer being provided between the secondsemiconductor portion and the pad unit, the first light emitting layerbeing provided between the second semiconductor portion and the secondsemiconductor layer; a second light emitting unit including a thirdsemiconductor layer, a fourth semiconductor layer, and a second lightemitting layer, the third semiconductor layer being provided between thepad unit and the first light emitting unit and including a thirdsemiconductor portion and a fourth semiconductor portion, the fourthsemiconductor portion being arranged with the third semiconductorportion in a direction crossing the first direction, the fourthsemiconductor layer being provided between the fourth semiconductorportion and the pad unit, the second light emitting layer being providedbetween the fourth semiconductor portion and the fourth semiconductorlayer; a first electrode provided between the pad unit and the secondlight emitting unit; an insulating support layer provided between thepad unit and the first electrode; a first conductive layer providedbetween the first light emitting unit and the second light emittingunit, the first conductive layer extending in the first direction andelectrically connected with the second semiconductor layer; a firstinter-light emitting unit dielectric layer provided between the firstlight emitting unit and the second light emitting unit and between thefirst conductive layer and the second light emitting unit, the firstinter-light emitting unit dielectric layer being light-transmissive; afirst connection electrode provided between the first semiconductorportion and the third semiconductor layer to electrically connect thefirst semiconductor portion and the third semiconductor layer, the firstconnection electrode piercing the first inter-light emitting unitdielectric layer in the first direction; a first dielectric layerprovided between the first connection electrode and the secondsemiconductor layer, between the first connection electrode and thefirst light emitting layer, and between the first connection electrodeand the first conductive layer; a second connection electrode providedbetween the third semiconductor portion and the first pad toelectrically connect the third semiconductor portion and the first pad,the second connection electrode piercing the insulating support layer inthe first direction; a second dielectric layer provided between thesecond connection electrode and the fourth semiconductor layer, betweenthe second connection electrode and the second light emitting layer, andbetween the second connection electrode and the first electrode; a thirdconnection electrode provided between the first conductive layer and thesecond pad to electrically connect the first conductive layer and thesecond pad, the third connection electrode piercing the firstinter-light emitting unit dielectric layer, the second light emittingunit and the insulating support layer in the first direction; a thirddielectric layer provided between the third connection electrode and thesecond light emitting unit and between the third connection electrodeand the first electrode; and a fourth connection electrode providedbetween the first electrode and the third pad to electrically connectthe first electrode and the third pad, the fourth connection electrodepiercing the insulating support layer in the first direction.
 20. Theelement according to claim 1, wherein the first light emitting unit hasa surface on a side opposite to the second light emitting unit, and thesurface on the side opposite to the second light emitting unit is asurface on a light extraction side.